Expression, purification and micelle reconstruction of the transmembrane domain of the human amyloid precursor protein for NMR studies / 生物工程学报

The multiple-step cleavage of amyloid precursor protein (APP) generates amyloid-β peptides (Aβ), highly toxic molecules causing Alzheimer's disease (AD). The nonspecific cleavage between the transmembrane region of APP (APPTM) and γ-secretase is the key step of Aβ generation. Reconstituting APPTM under physiologically-relevant conditions is crucial to investigate how it interacts with γ-secretase and for future AD drug discovery. Although producing recombinant APPTM was reported before, the large scale purification was hindered by the use of biological protease in the presence of membrane protein. Here, we expressed recombinant APPTM in Escherichia coli using the pMM-LR6 vector and recovered the fusion protein from inclusion bodies. By combining Ni-NTA chromatography, cyanogen bromide cleavage, and reverse phase high performance liquid chromatography (RP-HPLC), isotopically-labeled APPTM was obtained in high yield and high purity. The reconstitution of APPTM into dodecylphosphocholine (DPC) micelle generated mono dispersed 2D 15N-1H HSQC spectra in high quality. We successfully established an efficient and reliable method for the expression, purification and reconstruction of APPTM, which may facilitate future investigation of APPTM and its complex in more native like membrane mimetics such as bicelle and nanodiscs.

Epitope identification of calcitonin gene-related peptide antibodies based on ELISA and NMR methods / 中国生物制品学杂志

@#Objective To develop an indirect ELISA-based peptide scanning method combined with nuclear magnetic resonance(NMR)technique for the epitope identification of calcitonin gene-related peptide(CGRP)antibodies.Methods The antigen binding activities of two antibodies(new CGRP antibody and control antibody)were determined by indirect ELISA using each truncated CGRP fragment as coating antigen,and the linear epitope was analyzed according to the EC50value of four-parameter curve. Two-dimensional hydrogen-nitrogen correlation(2D1H-15N HSQC)spectrum of CGRP were acquired by NMR technique,and the binding of antibodies to the arginine of CGRP were analyzed through the disturbance of the antibodies to CGRP signals. Specific arginine modifications were detected by liquid chromatography-mass spectrum(LCMS) and NMR technique,and two arginine resonances were assigned on CGRP by correlating the rank order of the modification rate.ResultsThe antigen binding activities of two antibodies with CGRP(1-37),CGRP(19-37)and CGRP(25-37)showed dose-response relationships,and were fitted with four-parameter equation. However,there were no significant antigen binding with CGRP(1-18),CGRP(19-24)and CGRP(25-37)without C-terminal amide. The linear epitopes of both antibodies were located at the C-terminal of CGRP. The resonances of arginine ε-NH in 2D1H-15N HSQC spectrum disappeared in the presence of the control antibody;and the resonances appeared in the presence of the new antibody. The arginine R11 and R18 of CGRP could bind to the control antibody,but not to the new antibody. The NMR assignment for the arginine resonances were made by correlating the relative ranking of the modification rate where signals A and B arose from R11 ε-NH and R18 ε-NH respectively.ConclusionIn this study,the linear and conformational epitopes of new CGRP antibody and control antibody were identified based on the methods of ELISA and NMR,which may provide a theoretical basis for the design of the candidate therapeutic CGRP antibodies.

Identification of Synthetic Cannabinoid 5F-EDMB-PICA in Suspicious Herbal Products / 法医学杂志

Objective To study the qualitative analysis strategy for unknown synthetic cannabinoid in the suspicious herbal product when no reference substance is available. Methods The synthetic cannabinoid in herbal blend was extracted with methanol. The extract was concentrated by rotary evaporator and separated and purified by preparative liquid chromatography, to obtain high purity synthetic cannabinoid sample. Gas chromatography-mass spectrometry （GC-MS）, ultra-high performance liquid chromatography-quadrupole time-of-flight mass spectrometry （UPLC-QTOF-MS） and nuclear magnetic resonance （NMR） were used to determine the structure of the prepared compound. Results High purity unknown sample （10 mg） was obtained by preparative liquid chromatography. The sample was analyzed by GC-MS, UPLC-TOF-MS and NMR, and through spectrum analysis, the unknown synthetic cannabinoid was determined as 5F-EDMB-PICA. Conclusion The method to extract unknown synthetic cannabinoid from low content herbal products by preparative liquid chromatography was established, and the structure of the unknown sample was identified by comprehensive use of GC-MS, UPLC-QTOF-MS and NMR. The information will assist forensic laboratories in identifying this substance or other compounds with similar structures in their casework.

Encefalomielitis diseminada aguda posinfecciosa en un paciente con sospecha de infección por virus dengue / Postinfectious acute disseminated encephalomyelitis in a patient with suspected dengue virus infection

Introducción: La infección por virus dengue es considerada una de las arbovirosis de mayor prevalencia en los países tropicales. La encefalomielitis diseminada aguda es un trastorno inflamatorio desmielinizante y multifocal que afecta al sistema nervioso central, de inicio agudo y curso clínico monofásico. El proceso inflamatorio se encuentra mediado por mecanismos inmunológicos y su relación con infecciones por el virus dengue aún no se establece con claridad. Objetivo: Describir un caso clínico con manifestaciones del sistema nervioso central después de una probable infección por el virus dengue. Presentación del caso: Paciente femenina de 50 años, con antecedentes de hipertensión arterial controlada. Quince días después de un cuadro de fiebre de 4 días de duración, que posiblemente fue por una infección por el virus dengue, comienza con síntomas y signos de afectación neurológica caracterizadas por ligera irritabilidad, dificultad para la concentración en una actividad específica de la vida cotidiana. Progresivamente se nota dificultad motora en el hemicuerpo izquierdo además de encontrarse agitada y distraída, motivo por el cual se decide su ingreso hospitalario. Se realiza el diagnóstico a través de los hallazgos en el examen físico, los estudios positivos de resonancia magnética nuclear y el resultado positivo de la IgM de dengue en sangre. Tanto la evolución clínica como la respuesta al tratamiento con esteroides fueron favorables. Conclusiones: El evento ocurrido en este caso sugiere que los facultativos deben tener presente el diagnóstico de encefalomielitis diseminada aguda en pacientes que han tenido infección previa o alta sospecha de esta por el virus dengue(AU)

Introduction: Dengue virus infection is one of the most prevalent arboviruses in tropical countries. Acute disseminated encephalomyelitis is an inflammatory demyelinating multifocal disorder affecting the central nervous system. Its onset is acute and its clinical course monophasic. The inflammatory process is mediated by immunological mechanisms, and its relationship to dengue virus infections is still not clear. Objective: Describe a clinical case of central nervous system manifestations after probable dengue virus infection. Case presentation: Female 50-year-old patient with a history of controlled hypertension. Fifteen days after a 4-day fever episode, possibly due to dengue virus infection, the patient starts presenting neurological signs and symptoms, such as slight irritability and difficulty to concentrate on a specific activity of daily living. The patient notices progressive motor difficulty in her left hemibody and she feels agitated and distracted. It is therefore decided for her to be hospitalized. A diagnosis is made based on physical examination findings, positive nuclear magnetic resonance studies, and the positive result of the dengue IgM blood test. Both the patient's clinical evolution and her response to treatment with steroids were favorable. Conclusions: The event herein described suggests that physicians should consider the diagnosis of acute disseminated encephalomyelitis in patients with previous infection or high suspicion of infection with dengue virus(AU)

On the necessity of an integrative approach to understand protein structural dynamics / 浙江大学学报（英文版）（B辑：生物医学和生物技术）

Proteins are dynamic, fluctuating between multiple conformational states. Protein dynamics, spanning orders of magnitude in time and space, allow proteins to perform specific functions. Moreover, under certain conditions, proteins can morph into a different set of conformations. Thus, a complete understanding of protein structural dynamics can provide mechanistic insights into protein function. Here, we review the latest developments in methods used to determine protein ensemble structures and to characterize protein dynamics. Techniques including X-ray crystallography, cryogenic electron microscopy, and small angle scattering can provide structural information on specific conformational states or on the averaged shape of the protein, whereas techniques including nuclear magnetic resonance, fluorescence resonance energy transfer (FRET), and chemical cross-linking coupled with mass spectrometry provide information on the fluctuation of the distances between protein domains, residues, and atoms for the multiple conformational states of the protein. In particular, FRET measurements at the single-molecule level allow rapid resolution of protein conformational states, where information is otherwise obscured in bulk measurements. Taken together, the different techniques complement each other and their integrated use can offer a clear picture of protein structure and dynamics.

On the necessity of an integrative approach to understand protein structural dynamics / 浙江大学学报（英文版）（B辑：生物医学和生物技术）

Proteins are dynamic, fluctuating between multiple conformational states. Protein dynamics, spanning orders of magnitude in time and space, allow proteins to perform specific functions. Moreover, under certain conditions, proteins can morph into a different set of conformations. Thus, a complete understanding of protein structural dynamics can provide mechanistic insights into protein function. Here, we review the latest developments in methods used to determine protein ensemble structures and to characterize protein dynamics. Techniques including X-ray crystallography, cryogenic electron microscopy, and small angle scattering can provide structural information on specific conformational states or on the averaged shape of the protein, whereas techniques including nuclear magnetic resonance, fluorescence resonance energy transfer (FRET), and chemical cross-linking coupled with mass spectrometry provide information on the fluctuation of the distances between protein domains, residues, and atoms for the multiple conformational states of the protein. In particular, FRET measurements at the single-molecule level allow rapid resolution of protein conformational states, where information is otherwise obscured in bulk measurements. Taken together, the different techniques complement each other and their integrated use can offer a clear picture of protein structure and dynamics.

Plasma metabonomic study on the changes of dibutyl phthalate using ~1H NMR / 中国职业医学

OBJECTIVE: To screen small molecule metabolites of dibutyl phthalate( DBP) in the rat plasma using ~1H nuclear magnetic resonance( NMR) technology; and to clarify the changes of metabolites and possible mechanism in metabolic regulation of DBP in rats from the molecular level and the aspects of material and energy metabolism. METHODS: According to random number table method,twenty-four specific pathogen free SD male rats were divided into four groups: control group,low dose group,middle dose group and high dose group with the given dose of 0,500,1 000 and1 500 mg / kg of body mass,respectively. After giving DBP of gavage once a day for two weeks,the plasma samples were obtained,and ~1H NMR spectra was recorded. The plasma metabonomic profiles were analyzed using pattern recognition.Difference metabolites were screened by principal components analysis,partial least squares-discriminate analysis and orthogonal partial least squares-discriminate analysis. Biomarkers was screened by variable importance in the projection norm. RESULTS: There were changes of twelve important metabolites in the plasma metabonomic profiles between DBP treatment groups and control group. The differences of metabolites had dose-effect relationship. Plasma levels of high density lipoprotein cholesterol, low density lipoprotein cholesterol, hydrobutyrate, glycoprotein, citric acid, glucose,creatine phosphate,unsaturated fatty acid,tyrosine and phenylalanine were reduced( P < 0. 05),while lactic acid and pyruvic acid were increased( P < 0. 05). CONCLUSION: DBP induces the metabolic disorders including amino acid metabolism,lipid metabolism and energy metabolism.

Effect of gamma radiation on lipids by the TBARS and NMR

The aim of this work was to study the effect of gamma radiation on lipids by TBARS and NMR. The samples of raw whole milk were subjected to gamma radiation from Co60 in doses of 1, 2 and 3 kGy and the production of rancidity was studied through Nuclear Magnetic Resonance (NMR) and Thiobarbituric Acid Test (2-TBARS). The TBARS values increased according to the intensity of the radiation dose applied at the samples, demonstrating correlation between the radiation dose and the production of lipid oxidation. This was confirmed by NMR with the formation of peaks of aldehydes and ketones that were small and similar in the doses of 1 and 2 kGy. In the dose of 3 kGy, the total degradation of milk fat was observed. A correlation between the NMR and 2-TBA was detected.