Production and Characterization of ACE Inhibitory and Anti-Diabetic Peptides from Buffalo and Camel Milk Fermented with Lactobacillus and Yeast: A Comparative Analysis with In Vitro, In Silico, and Molecular Interaction Study.

The investigation aimed at assessing a comparative study on the production and characterization of ACE inhibitory, anti-diabetic, and anti-inflammatory activities, along with the production of ACE inhibitory and anti-diabetic peptides through the fermentation of buffalo and camel milk by Limosilactobacillus fermentum (KGL4) and Saccharomyces cerevisiae (WBS2A). The angiotensin-converting enzyme (ACE) inhibitory and anti-diabetic properties were evaluated at particular time intervals (12, 24, 36, and 48 h) at 37 °C, and we discovered maximum activity at 37 °C after 48 h of incubation. The maximum ACE inhibitory, lipase inhibitory activities, alpha-glucosidase inhibitory, and alpha-amylase inhibitory activities were found in the fermented camel milk (77.96 ± 2.61, 73.85 ± 1.19, 85.37 ± 2.15, and 70.86 ± 1.02), as compared to the fermented buffalo milk (FBM) (75.25 ± 1.72, 61.79 ± 2.14, 80.09 ± 0.51, and 67.29 ± 1.75). Proteolytic activity was measured with different inoculation rates (1.5%, 2.0%, and 2.5%) and incubation times (12, 24, 36, and 48 h) to optimize the growth conditions. Maximum proteolysis was found at a 2.5% inoculation rate and at a 48 h incubation period in both fermented buffalo (9.14 ± 0.06) and camel milk (9.10 ± 0.17). SDS-PAGE and 2D gel electrophoresis were conducted for protein purification. The camel and buffalo milk that had not been fermented revealed protein bands ranging from 10 to 100 kDa and 10 to 75 kDa, respectively, whereas all the fermented samples showed bands ranging from 10 to 75 kDa. There were no visible protein bands in the permeates on SDS-PAGE. When fermented buffalo and camel milk were electrophoresed in 2D gel, 15 and 20 protein spots were detected, respectively. The protein spots in the 2D gel electrophoresis ranged in size from 20 to 75 kDa. To distinguish between different peptide fractions, water-soluble extract (WSE) fractions of ultrafiltration (3 and 10 kDa retentate and permeate) of fermented camel and buffalo milk were employed in RP-HPLC (reversed-phase high-performance liquid chromatography). The impact of fermented buffalo and camel milk on inflammation induced by LPS (lipopolysaccharide) was also investigated in the RAW 264.7 cell line. Novel peptide sequences with ACE inhibitory and anti-diabetic properties were also analyzed on the anti-hypertensive database (AHTDB) and bioactive peptide (BIOPEP) database. We found the sequences SCQAQPTTMTR, EMPFPK, TTMPLW, HPHPHLSFMAIPPK, FFNDKIAK, ALPMHIR, IPAVFK, LDQWLCEK, and AVPYPQR from the fermented buffalo milk and the sequences TDVMPQWW, EKTFLLYSCPHR, SSHPYLEQLY, IDSGLYLGSNYITAIR, and FDEFLSQSCAPGSDPR from the fermented camel milk.

Pilot investigation of magnetic nanoparticle-based immobilized metal affinity chromatography for efficient enrichment of phosphoproteoforms for mass spectrometry-based top-down proteomics.

Protein phosphorylation is a vital and common post-translational modification (PTM) in cells, modulating various biological processes and diseases. Comprehensive top-down proteomics of phosphorylated proteoforms (phosphoproteoforms) in cells and tissues is essential for a better understanding of the roles of protein phosphorylation in fundamental biological processes and diseases. Mass spectrometry (MS)-based top-down proteomics of phosphoproteoforms remains challenging due to their relatively low abundance. Herein, we investigated magnetic nanoparticle-based immobilized metal affinity chromatography (IMAC, Ti4+, and Fe3+) for selective enrichment of phosphoproteoforms for MS-based top-down proteomics. The IMAC method achieved reproducible and highly efficient enrichment of phosphoproteoforms from simple and complex protein mixtures. It outperformed one commercial phosphoprotein enrichment kit regarding the capture efficiency and recovery of phosphoproteins. Reversed-phase liquid chromatography (RPLC)-tandem mass spectrometry (MS/MS) analyses of yeast cell lysates after IMAC (Ti4+ or Fe3+) enrichment produced roughly 100% more phosphoproteoform identifications compared to without IMAC enrichment. Importantly, the phosphoproteoforms identified after Ti4+-IMAC or Fe3+-IMAC enrichment correspond to proteins with much lower overall abundance compared to that identified without the IMAC treatment. We also revealed that Ti4+-IMAC and Fe3+-IMAC could enrich different pools of phosphoproteoforms from complex proteomes and the combination of those two methods will be useful for further improving the phosphoproteoform coverage from complex samples. The results clearly demonstrate the value of our magnetic nanoparticle-based Ti4+-IMAC and Fe3+-IMAC for advancing top-down MS characterization of phosphoproteoforms in complex biological systems.

Direct deamidation analysis of intact adeno-associated virus serotype 9 capsid proteins using reversed-phase liquid chromatography.

Recombinant adeno-associated viral (AAV) vectors have taken center stage as gene delivery vehicles for gene therapy. Asparagine deamidation of AAV capsid proteins has been reported to reduce vector stability and potency of AAV gene therapy products. Deamidation of asparagine residue is a common post-translational modification of proteins that is detected and quantified by liquid chromatography-tandem mass spectrometry (LC-MS)-based peptide mapping. However, artificial deamidation can be spontaneously induced during sample preparation for peptide mapping prior to LC-MS analysis. We have developed an optimized sample preparation method to reduce and minimize deamidation artifacts induced during sample preparation for peptide mapping, which typically takes several hours to complete. To shorten turnaround time of deamidation results and to avoid artificial deamidation, we developed orthogonal RPLC-MS and RPLC-fluorescence detection methods for direct deamidation analysis at the intact AAV9 capsid protein level to routinely support downstream purification, formulation development, and stability testing. Similar trends of increasing deamidation of AAV9 capsid proteins in stability samples were observed at the intact protein level and peptide level, indicating that the developed direct deamidation analysis of intact AAV9 capsid proteins is comparable to the peptide mapping-based deamidation analysis and both methods are suitable for deamidation monitoring of AAV9 capsid proteins.

Peptidomics analysis of Jiang-Flavor Daqu from high-temperature fermentation to mature and in different preparation season.

Jiang-Flavor Daqu (JFDQ) is a grain-type fermented starter for brewing Chinese liquor. Peptides, the metabolites of proteins in JFDQ, are important for the quality and flavor of JFDQ or even the liquor. The peptide variations in the progress of JFDQ preparation were investigated using RPLC-MS/MS. The JFDQ after high-temperature fermenting (HTF_SU) and after ripening (M_SU), as well as the mature JFDQ prepared in spring (M_SP) and in summer (M_SU), were compared respectively. These two groups were investigated from peptides, precursor proteins, abundance, interactions, and potential antimicrobial peptides (pAMPs). A total of 177, 158, and 262 peptides from HTF_SU, M_SP, and M_SU were identified, respectively. Significant differences (P < 0.01) in the abundance of shared peptides were found in different fermentation stage group (HTF_M), and stronger positive correlations were observed in different preparation season group (MSP_MSU). The interactions of the shared peptides in HTF_M and in MSP_MSU were investigated respectively. In addition, 8 pAMPs in HTF_SU, 5 in M_SP, and 22 in M_SU were predicted using CAMPR3, and their core functional regions were analyzed. This systematic study demonstrated the influences of fermentation stage and preparation season on the peptide profiles in JFDQ, which would provide theoretical guidance and be helpful for JFDQ production. SIGNIFICANCE: Peptidomics analysis showed that the peptide profiles of JFDQ varied in different fermentation stages and different preparation seasons, which mainly resulted from the peptides with high abundance, high interaction degrees, and potential antimicrobial activity, as well as the important precursor proteins such as glutens. This systematic study would benefit for the insufficiency of peptide research of JFDQ till now, and provide theoretical guidance for JFDQ production.

Bispecific antibody characterization by a combination of intact and site-specific/chain-specific LC/MS techniques.

Bispecific antibodies (bsAbs) are considered as an important class of biopharmaceutical drugs, with about 160 products in clinical trials. From an analytical point of view, the correct chain-association is one of the most critical challenge to monitor during bsAbs development and production. In the present study, a full analytical workflow has been developed based on the use of various chromatographic modes: size exclusion chromatography (SEC), ion exchange chromatography (IEX), reversed phase liquid chromatography (RPLC), and hydrophilic interaction chromatography (HILIC), all combined with high resolution mass spectrometry (MS). This analytical strategy was applied to Hemlibra® (emicizumab), which is certainly the most successful commercial bsAb to date. Using this strategy, it was possible to monitor the presence of mispaired bsAb species and detect and identify additional post-translational modifications (PTMs).

Estudo do efeito de estatinas e antiplaquetários na evolução do infarto agudo do miocárdio: uma abordagem metabolômica multiplataform / Effect of statins and antiplatelets in the evolution of acute myocardium infarction: a multiplatform metabolomics approach

O infarto agudo do miocárdio (IAM) é a maior causa de mortalidade no mundo. A oclusão coronária determina a necrose completa de cardiomiócitos (células musculares cardíacas) durante as primeiras horas do IAM. Porém, mesmo após a perda de massa de miocárdio viável cessar, a região infartada pode se expandir ou contrair no decorrer das primeiras semanas, afetando o prognóstico dos pacientes. Alguns tratamentos podem auxiliar na recuperação e melhoria do prognóstico desses pacientes, como o uso de estatinas e antiplaquetários, que quando utilizados em conjunto, proporcionam efeitos sinérgicos. O presente estudo investigou e comparou, através da óptica da metabolômica global multiplataforma, tratamentos concomitantes de estatinas (sinvastatina ou rosuvastatina) e antiplaquetários bloqueadores do receptor de ADP (clopidogrel ou ticagrelor), em pacientes que sofreram IAM. Foram coletadas amostras de plasma e urina de cerca 40 pacientes tratados com clopidrogrel e sinvastatina ou ticagrelor e rosuvastatina no Hospital São Paulo em diferentes períodos (basal, 1 mês e 6 meses após IAM). Amostras de plasma (basal e 1 mês) foram analisadas por RPLC-MS nos modos de ionização positivo e negativo, GC-MS e CEMS. Amostras de urina (basal, 1 mês e 6 meses) foram analisadas por RPLC-MS no modo de ionização positivo e HILIC-MS nos modos de ionização positivo e negativo. A abordagem metabolomica global multiplataforma evidenciou alterações no metabolismo de diferentes vias pelos dois tratamentos. Os dois tratamentos proporcionaram um efeito pronunciado no metabolismo de diferentes lipídios, como glicerolipídios, esfingolipídios, glicerofosfolipídios e ácidos graxos, sendo que a combinação rosuvastatina e ticagrelor resultou num efeito mais acentuado. Já o tratamento com clopidogrel e sinvastatina alterou de maneira mais pronunciada o metabolismo de aminoácidos ramificados e de acilcarnitinas de cadeia curta. Observou-se ainda a alteração de possíveis biomarcadores relatados na literatura como associados a problemas cardiovasculares, como hipoxantina, ácido 2-hidroxibutírico, algumas espécies de ceramidas, fosfatidilcolinas e acilcarnitinas de cadeia curta

cute myocardium infarction (AMI) is the main mortality cause in the world. The coronary occlusion determines the complete necrosis of cardiomyocytes (cardiac muscle cells) during the first hours of AMI. However, even after the loss of viable myocardial mass ceases, the infarcted area may still expand or contract during the first weeks after AMI, affecting the patient prognosis. Some treatments may assist patient recovery and improve prognostic, such as statins and antiplatelets which, when combined, provide synergic effects. This study investigated and compared, by untargeted multiplatform metabolomics, simultaneous treatments of statins (simvastatin or rosuvastatin) and ADP receptor antagonist antiplatelets (clopidogrel or ticagrelor) in patients that suffered AMI. Plasma and urine samples from around 40 patients treated with clopidogrel and simvastatin or ticagrelor and rosuvastatin were collected in Hospital Sao Paulo at different time points (basal, 1 month, 6 months after AMI). Plasma samples (basal and 1 month) were analyzed by RPLC-MS in positive and negative ionization modes, GC-MS and CE-MS. Urine samples (basal, 1 month, 6 months) were analyzed by RPLC-MS in positive ionization mode and by HILIC-MS in positive and negative ionization modes. The untargeted multiplatform metabolomics approach has shown that different metabolic pathways have been altered by the two treatments. Both treatments had a profound impact on the metabolism of different lipids, such as glycerolipids, sphingolipids, glycerophospholipids, and fatty acids. However, the combined treatment using rosuvastatin and ticagrelor impacted the most the lipid pathways. On the other hand, clopidogrel and simvastatin treatment affected more intensily the branched chain amino acids and short chain acylcarnitines metabolisms. Reported biomarkers in the literature related to cardiovascular diseases were also observed in this study, such as hypoxanthine, 2-hydroxybutyric acid, some species of ceramides, phosphatidylcholines and short chain acylcarnitines

Aptamer-based immunoaffinity LC-MS using an ultra-short column for rapid attomole level quantitation of intact mAbs.

Quantification of proteins in biofluids has largely involved either traditional ligand binding assays or "bottom-up" mass spectrometry. Recently, top-down mass spectrometry using reversed-phase liquid chromatography (RPLC) paired with high-resolution mass spectrometry (HRMS) has emerged as a promising technique, due to the potential of better identification of post-translational modifications (PTMs), lack of downstream interferences, and less time-consuming sample preparation and analysis times. However, it can be difficult with this approach to robustly obtain high-fidelity MS data, especially when pushing for low limits of detection. To address these issues, we developed a chromatographic device with an optimized form factor and stationary phase to improve protein recovery, while reducing run times. We have observed that by using this device, it is possible to achieve attomole quantitation of mAbs without the addition of carrier proteins and with over three-fold higher throughput than columns employed in previous studies. Moreover, we have devised a novel affinity capture method, based on repurposing a unique aptamer ligand that can give 93% recovery of mAb using only a 2 h incubation. When hyphenated together, these two technologies greatly improve the ability to analyze proteins in complex matrices.

Alternative mobile phase additives for the characterization of protein biopharmaceuticals in liquid chromatography - Mass spectrometry.

When analyzing large complex protein biopharmaceuticals, ion-pairing agents imparting low pH are widely used as mobile phase additives to improve the chromatographic performance. However, one of the most effective additives in RPLC and HILIC, trifluoroacetic acid (TFA), is known as a strong suppressor of the MS signal and limits its use in hyphenated techniques. In this study, we evaluated a wide range of acidic additives to find alternatives to TFA that provided comparable chromatographic performance and improved MS sensitivity. It was observed that stronger acidic additives were required for intact level analysis compared to subunit level analysis and that the additive nature had a larger impact on the chromatographic performance in HILIC mode compared to RPLC. Therefore, four additives were identified as valuable alternatives to TFA in RPLC mode, namely, difluoroacetic acid (DFA), dichloroacetic acid (DClAA), trichloroacetic acid (TClAA), and methanesulfonic acid (MSA). Only one of these additives provided acceptable performance in HILIC mode, namely, TClAA. After evaluation of the MS performance, TClAA was discarded due to the apparent loss of intensity in both RPLC-MS and HILIC-MS mode. Together, these results demonstrate that for HILIC-MS analysis TFA remains the gold standard additive. However, DFA was found as promising alternative to TFA for RPLC-MS analysis and could play an important role in the development of methods for the characterization of the increasingly complex protein biopharmaceuticals.

A abordagem metabolômica na indicação do tratamento de estenose de junção ureteropélvica em crianças / Metabolomics approach in the treatment of ureteropelvic junction stenosis in children

Estenose de Junção Ureteropélvica (JUP) é uma doença caracterizada pelo bloqueio do fluxo de urina da pelve renal (porção proximal do ureter no rim) ao ureter, tubo que liga o rim à bexiga. Essa formação congênita é uma das maiores causas de dilatação do rim (hidronefrose) em recém-nascidos e, em alguns casos, pode causar danos mais severos ao órgão. A hidronefrose causada pela estenose de JUP pode desaparecer espontaneamente sem perda da função renal, entretanto, é preciso um acompanhamento clínico. Por outro lado, em casos mais severos, onde a dilatação pode causar danos maiores ao rim, um tratamento cirúrgico se faz necessário. Embora existam métodos para o diagnóstico da estenose de JUP, como ultrassonografia, tomografia computadorizada, ressonância e cintilografia, é um grande desafio diferenciar os pacientes que requerem um tratamento cirúrgico e os que necessitam apenas de um acompanhamento convencional. A metabolômica global, que investiga de modo comparativo o conjunto de metabólitos de baixa massa molecular expressos em indivíduos em condições pré-selecionadas, tem o potencial de servir como ferramenta diagnóstica para os pacientes com estenose de JUP e, consequentemente, auxiliar na tomada de decisão entre um acompanhamento clínico ou tratamento cirúrgico. Assim sendo, no presente trabalho, três grupos de pacientes com estenose de JUP, pré-diagnosticados por métodos convencionais, foram investigados sob a perspectiva da metabolômica global, por meio de análises de urina, utilizando cromatografia gasosa e cromatografia líquida, ambas acoplada à espectrometria de massas (GC-MS e RPLC10 MS, respectivamente): pacientes que requerem tratamento cirúrgico (CIR), pacientes que requerem acompanhamento clínico (CLI), e indivíduos sãos (CON). Os resultados mostram que é possível encontrar metabólitos discriminantes entre todas as comparações (CON x CLI, CON x CIR e CLI x CIR); os metabólitos encontrados nas análises multivariada e univariada foram utilizados para construção da curva ROC, para confirmar a possibilidade de utilização desses compostos como biomarcadores. Foram observadas alterações em rotas metabólicas importantes para o bom funcionamento das funções renais, principalmente entre a comparação mais desafiadora (CLI x CIR), como o metabolismo da fenilalanina, da tirosina, da beta-alanina, dos aminoaçúcares e dos nucleotídeos. Há indícios de que o ciclo de Krebs também sofre alteração. Os resultados obtidos podem servir como ponto de partida para uma futura análise alvo e validação biológica

Ureteropelvic junction (UPJ) stenosis is a disease characterized by the interruption of the flow of urine from the renal pelvis (proximal part of ureter in the kidney) to the ureter, tube that links the kidney to bladder. That congenital formation is one of the main causes of kidney dilation (hydronephrosis) in newborns and, sometimes, can cause more serious damage to the organ. The hydronephrosis caused by UPJ stenosis can disappear spontaneously without compromising renal function, although a clinical follow-up is required. On the other hand, in more serious cases, when dilation can induce larger damage to the kidney, surgery intervention is necessary. Although there are methods to diagnose UPJ stenosis, such as ultrasound, computed tomography, resonance and scintigraphy, it is still a great challenge to distinguish patients that require surgery from those whose a clinical follow-up suffices. Global metabolomics, a method that investigates in a comparative manner the set of low molecular mass metabolites expressed by an individual in pre-selected conditions, has the potential to function as a diagnostic tool for patients with UPJ stenosis to support decisions about patient treatment, i.e., surgery versus clinical follow-up. In this work, three groups of UPJ stenosis patients were investigated with the aid of global metabolomics using urine analysis by gas chromatography and liquid chromatography coupled to mass spectrometry (GC-MS and RPLC-MS, respectively): one group consisted of UPJ stenosis patients requiring clinical follow-up (CLI), other group UPJ stenosis patients requiring surgery intervention (CIR) and a third group comprising healthy individuals, the control group (CON).12 The results show that it was possible to find discriminant metabolites among all pairwise comparisons (CON versus CLI, CON versus CIR and CLI versus CIR). The metabolites found by multivariate and univariate analyses were used to build ROC curves, to confirm whether it is possible to use them as biomarkers. Alterations in metabolic pathways that are important for the good maintenance of kidney functions were found, especially in the most challenged comparison (CLI versus CIR), such as the metabolism of phenylalanine, tyrosine, beta-alanine, amino acids and nucleotides. There are evidences that Krebs cycle was also impacted. The results obtained here can serve as a starting point to future targeted analysis and biological validation

Using an Untargeted Metabolomics Approach to Identify Salivary Metabolites in Women with Breast Cancer.

Metabolic alterations are a hallmark of the malignant transformation in cancer cells, which is characterized by multiple changes in metabolic pathways that are linked to macromolecule synthesis. This study aimed to explore whether salivary metabolites could help discriminate between breast cancer patients and healthy controls. Saliva samples from 23 breast cancer patients and 35 healthy controls were subjected to untargeted metabolomics using liquid chromatography-quadrupole time-of-flight mass spectrometry and a bioinformatics tool (XCMS Online), which revealed 534 compounds, characterized by their retention time in reverse-phase liquid chromatography and by the m/z ratio detected, that were shared by the two groups. Using the METLIN database, 31 compounds that were upregulated in the breast cancer group (p < 0.05) were identified, including seven oligopeptides and six glycerophospholipids (PG14:2, PA32:1, PS28:0, PS40:6, PI31:1, and PI38:7). In addition, pre-treatment and post-treatment saliva samples were analyzed for 10 patients who experienced at least a partial response to their treatment. In these patients, three peptides and PG14:2 were upregulated before but not after treatment. The area under the curve, sensitivity, and specificity for PG14:2 was 0.7329, 65.22%, and 77.14%, respectively. These results provide new information regarding the salivary metabolite profiles of breast cancer patients, which may be useful biomarkers.

The expanding role of mass spectrometry in the field of vaccine development.

Biological mass spectrometry has evolved as a core analytical technology in the last decade mainly because of its unparalleled ability to perform qualitative as well as quantitative profiling of enormously complex biological samples with high mass accuracy, sensitivity, selectivity and specificity. Mass spectrometry-based techniques are also routinely used to assess glycosylation and other post-translational modifications, disulfide bond linkage, and scrambling as well as for the detection of host cell protein contaminants in the field of biopharmaceuticals. The role of mass spectrometry in vaccine development has been very limited but is now expanding as the landscape of global vaccine development is shifting towards the development of recombinant vaccines. In this review, the role of mass spectrometry in vaccine development is presented, some of the ongoing efforts to develop vaccines for diseases with global unmet medical need are discussed and the regulatory challenges of implementing mass spectrometry techniques in a quality control laboratory setting are highlighted.

[Comparing nanoflow reversed-phase liquid chromatography-tandem mass spectrometry and capillary zone electrophoresis-tandem mass spectrometry for top-down proteomics].

One of the major shortcomings in top-down proteomics is the lack of efficient separations for intact proteins that can be effectively coupled to mass spectrometry. Capillary zone electrophoresis (CZE) and nanoflow reversed-phase liquid chromatography (nanoRPLC) are two methods that can be coupled to mass spectrometry directly and have been recently advanced in terms of their ability to separate intact proteins in complex biological mixtures. In this work, for the first time, we compared the state-of-the-art nanoRPLC-MS/MS and CZE-MS/MS platforms for top-down characterization of a standard protein mixture and an Escherichia coli (E. coli) proteome sample. CZE-MS produced comparable signals of standard proteins to RPLC-MS with 10-times less sample consumption. Interestingly, the proteins in RPLC-MS tended to have higher charge states than in CZE-MS, most likely due to the high acetonitrile concentration in RPLC mobile phase, leading to the more extensive unfolding of proteins in RPLC compared to in CZE. CZE-MS/MS identified 159 proteins and 513 proteoforms using 1-µg E. coli proteins in a single run and outperformed RPLC-MS/MS using 1-µg E. coli proteins in terms of protein and proteoform identifications (159 vs. 105 proteins and 513 vs. 277 proteoforms). The RPLC-MS/MS using 8-µg E. coli proteins identified 245 proteins and 1004 proteoforms in a single run, and the data was much better than that from CZE-MS/MS (1-µg E. coli proteins) regarding the number of identifications because of the 8-times higher sample loading amount and significantly wider separation window of RPLC-MS/MS compared to CZE-MS/MS.

Accurate mass and retention time library of serum lipids for type 1 diabetes research.

Dysregulated lipid species are linked to various disease pathologies and implicated as potential biomarkers for type 1 diabetes (T1D). However, it is challenging to comprehensively profile the blood specimen lipidome with full structural details of every lipid molecule. The commonly used reversed-phase liquid chromatography-tandem mass spectrometry (RPLC-MS/MS)-based lipidomics approach is powerful for the separation of individual lipid species, but lipids belonging to different classes may still co-elute and result in ion suppression and misidentification of lipids. Using offline mixed-mode and RPLC-based two-dimensional separations coupled with MS/MS, a comprehensive lipidomic profiling was performed on human sera pooled from healthy and T1D subjects. The elution order of lipid molecular species on RPLC showed good correlations to the total number of carbons in fatty acyl chains and total number of double bonds. This observation together with fatty acyl methyl ester analysis was used to enhance the confidence of identified lipid species. The final T1D serum lipid library database contains 753 lipid molecular species with accurate mass and RPLC retention time uniquely annotated for each of the species. This comprehensive human serum lipid library can serve as a database for high-throughput RPLC-MS-based lipidomic analysis of blood samples related to T1D and other childhood diseases. Graphical abstract.

Direct Analysis of Protein S-Acylation by Mass Spectrometry.

Dynamic and reversible protein S-acylation, most commonly occurring as S-palmitoylation, plays an important role in protein/membrane association and the regulation of intracellular signaling via cycles of palmitoylation and depalmitoylation. Direct analysis of protein S-acylation by mass spectrometry (MS) offers several benefits over indirect detection methods in that it can definitively determine the location and nature of the acyl modification, and is not prone to false discoveries. However, characterization of acyl proteins is challenging because of the tendency of acyl loss during sample preparation and tandem MS analysis. In this chapter, we present a sample preparation protocol that preserves labile acyl modifications and an LC-MS/MS workflow for detection of S-acylation with high confidence and sensitivity.

A Rapid High-Sensitivity Reversed-Phase Ultra High Performance Liquid Chromatography Mass Spectrometry Method for Assessing Polysorbate 20 Degradation in Protein Therapeutics.

Polysorbate 20 (PS20), a widely used surfactant in protein therapeutics, has been reported to undergo hydrolytic degradation during product storage, causing the release of free fatty acids. The accumulation of free fatty acids in protein therapeutics was found to result in the formation of particles due to their limited aqueous solubility at 2°C-8°C. Quantitation of free fatty acids originating from PS20 degradation is thus important during bioprocess optimization and stability testing in formulation development to ensure optimum PS20 stability as well as product and process consistency in final drug products. This work reports the development of a simple and robust, high-throughput, reversed-phase ultra high performance liquid chromatography mass spectrometry method for high-sensitivity quantitation of lauric acid and myristic acid by using isotope-labeled fatty acid internal standards. The high sensitivity (<100 ng/mL for lauric acid) and suitable precision (intermediate precision relative standard deviation of 11%) of this method enable accurate detection of lauric acid produced from the degradation of less than 1% of PS20 in a 0.2-mg/mL formulation. Using accelerated thermal stability testing, this method identifies processes that exhibit fast PS20 degradation within only days and consequently allows faster iterative optimization of the process.

Natural compounds analysis using liquid and supercritical fluid chromatography hyphenated to mass spectrometry: Evaluation of a new design of atmospheric pressure ionization source.

The MS hyphenation performance of UniSpray®, a new design of atmospheric pressure ionization source was evaluated in both SFC and RPLC modes. Sensitivity, stability, versatility and matrix effects offered by the UniSpray were assessed in positive and negative ionization modes and systematically compared to an electrospray source (ESI) using 120 natural compounds covering an extended chemical space. In a first instance, a multivariate approach was used to screen and optimize the UniSpray source settings to maximize detection sensitivity. The position of the source capillary against the fixed charged rod was highlighted as the major parameter affecting the detection sensitivity. The sensitivity improvement in Unispray vs. ESI strongly depends on the compounds chemical class and the chromatographic mode. For a few compounds (i.e. anabasine, theanine, caproic acid, fumaric acid and protopanaxatriol), up to a 10-fold increase in sensitivity was noticed with UniSpray. The signal stability over multiple injections was also found to be equivalent between both sources with RSD values on peak intensity lower than 14% on >100 injections, in both chromatographic modes. On complex plant extract, the matrix effects occurring from the secondary metabolites were also found to be comparable between ESI and UniSpray, at least in the positive ionization mode. However, a systematic decrease of MS signal intensity was observed in SFC mode when compounds were ionized using UniSpray in the negative ion mode.

High-temperature LC-MS/MS of permethylated glycans derived from glycoproteins.

Various glycomic analysis methods have been developed due to the essential roles of glycans in biological processes as well as the potential application of glycomics in biomarker discovery in many diseases. Permethylation is currently considered to be one of the most common derivatization methods in MS-based glycomic analysis. Permethylation not only improves ionization efficiency and stability of sialylated glycans in positive mode but also allows for enhanced separation performance on reversed-phase liquid chromatography (RPLC). Recently, RPLC-MS analysis of permethylated glycans exhibited excellent performance in sensitivity and reproducibility and became a widely-applied comprehensive strategy in glycomics. However, separating permethylated glycans by RPLC always suffers from peak broadening for high-molecular-weight branched glycans, which probably due to the low exchange rate between the stationary phase and mobile phase limited by intermolecular interactions of the methyl groups associated with the branching of the glycan structures. In this study, we employed high separation temperature conditions for RPLC of permethylated glycans, thus achieving enhanced peak capacity, improving peak shape, and enhancing separation efficiency. Additionally, partial isomeric separation were observed in RPLC of permethylated glycans at high-temperature. Mathematical processing of the correlation between retention time and molecular weight also revealed the advantage of high-temperature LC method for both manual and automatic glycan identification.

A sensitive multidimensional method for the detection, characterization, and quantification of trace free drug species in antibody-drug conjugate samples using mass spectral detection.

Conjugation processes and stability studies associated with the production and shelf life of antibody-drug conjugates (ADCs) can result in free (non-conjugated) drug species. These free drug species can increase the risk to patients and reduce the efficacy of the ADC. Despite stringent purification steps, trace levels of free drug species may be present in formulated ADCs, reducing the therapeutic window. The reduction of sample preparation steps through the incorporation of multidimensional techniques has afforded analysts more efficient methods to assess trace drug species. Multidimensional methods coupling size-exclusion and reversed phase liquid chromatography with ultra-violet detection (SEC-RPLC/UV) have been reported, but offer limited sensitivity and can limit method optimization. The current study addresses these challenges with a multidimensional method that is specific, sensitive, and enables method control in both dimensions via coupling of an on-line solid phase extraction column to RPLC with mass spectral detection (SPE-RPLC/MS). The proposed method was evaluated using an antibody-fluorophore conjugate (AFC) as an ADC surrogate to brentuximab vedotin and its associated parent maleimide-val-cit-DSEA payload and the derived N-acetylcysteine adduct formed during the conjugation process. Assay sensitivity was found to be 2 orders more sensitive using MS detection in comparison to UV-based detection with a nominal limit of quantitation of 0.30 ng/mL (1.5 pg on-column). Free-drug species were present in an unadulterated ADC surrogate sample at concentrations below 7 ng/mL, levels not detectable by UV alone. The proposed SPE-RPLC/MS method provides a high degree of specificity and sensitivity in the assessment of trace free drug species and offers improved control over each dimension, enabling straightforward integration into existing or novel workflows.

Metabolomics changes in a rat model of obstructive jaundice: mapping to metabolism of amino acids, carbohydrates and lipids as well as oxidative stress.

The study examined the global metabolic and some biochemical changes in rats with cholestasis induced by bile duct ligation (BDL). Serum samples were collected in male Wistar rats with BDL (n = 8) and sham surgery (n = 8) at day 3 after surgery for metabolomics analysis using a combination of reversed phase chromatography and hydrophilic interaction chromatography (HILIC) and quadrupole-time-of-flight mass spectrometry (Q-TOF MS). The serum levels of malondialdehyde (MDA), total antioxidative capacity (T-AOC), glutathione (GSH) and glutathione disulfide (GSSG), the activities of superoxide dismutase (SOD) and glutathion peroxidase (GSH-Px) were measured to estimate the oxidative stress state. Key changes after BDL included increased levels of l-phenylalanine, l-glutamate, l-tyrosine, kynurenine, l-lactic acid, LysoPC(c) (14:0), glycine and succinic acid and decreased levels of l-valine, PC(b) (19:0/0:0), taurine, palmitic acid, l-isoleucine and citric acid metabolism products. And treatment with BDL significantly decreased the levels of GSH, T-AOC as well as SOD, GSH-Px activities, and upregulated MDA levels. The changes could be mapped to metabolism of amino acids and lipids, Krebs cycle and glycolysis, as well as increased oxidative stress and decreased antioxidant capability. Our study indicated that BDL induces major changes in the metabolism of all 3 major energy substances, as well as oxidative stress.

Systematic evaluation of mobile phase additives for the LC-MS characterization of therapeutic proteins.

Trifluoroacetic acid (TFA) is commonly used as mobile phase additive for the analysis of proteins in reversed phase liquid chromatography (RPLC). Due to its interesting features, it provides symmetrical and narrow peak shapes for proteins, but decreases mass spectrometric sensitivity through ion-pairing and spray destabilizing. Since RPLC-MS is an important technique for the characterization of proteins, some alternative MS-compatible mobile phases may be required. The aim of this study was to evaluate various acidic and basic mobile phase additives for the LC-MS analysis of therapeutic proteins possessing molecular weight between 5 and 150kDa. At the end, 10mM formate buffer pH 3 was found to be the most promising alternative, since it provided acceptable peak shapes in most cases, together with an average improvement of MS sensitivity by 5-times, compared to TFA.