Incorporation of automated buffer exchange empowers high-throughput protein and plasmid purification for downstream uses.

The continued acceleration of time-to-market product development and rising demand for biotherapeutics have hastened the need for higher throughput within the biopharmaceutical industry. Automated liquid handlers (ALH) are increasingly popular due to flexible programming that enables processing of multiple samples with an array of functions. This flexibility is useful in streamlining research that requires chromatographic procedures to achieve product purity for downstream analysis. However, purification of biologics often requires additional off-deck buffer exchange steps due to undesirable elution conditions such as high acid or high salt content. Expanding the capability of ALHs to perform purification in sequence with buffer exchange would, therefore, increase workflow efficiency by eliminating the need for manual intervention, thus expediting sample preparation. Here we demonstrate two different automated purifications using pipet-based dispersive solid-phase extraction (dSPE). The first is an affinity purification of His-tagged proteins from bacterial lysate. The second is an anion-exchange purification of plasmid DNA. Both methods are followed by buffer exchange performed by an ALH. Percent recoveries for the three purified recombinant proteins ranged from 51 ± 1.2 to 86 ± 10%. The yields were inversely correlated to starting sample load and protein molecular weight. Yields for plasmid purification ranged between 11.4 ± 0.8 and 13.7 ± 0.9 µg, with the largest plasmid providing the highest yield. Both programs were rapid, with protein purification taking <80 min and plasmid purification <60 min. Our results demonstrate that high-quality, ready-to-use biologics can be obtained rapidly from a crude sample after two separate chromatographic processes without manual intervention.

Automated multi-attribute method sample preparation using high-throughput buffer exchange tips.

RATIONALE: The multi-attribute method (MAM) has become a valuable mass spectrometry (MS)-based tool that can identify and quantify the site-specific product attributes and purity information for biotherapeutics such as monoclonal antibodies (mAbs) and fusion molecules in recent years. As we expand the use of the MAM at various stages of drug development, it is critical to enhance the sample preparation throughput without additional chemical modifications and variability. METHODS: In this study, a fully automated MAM sample preparation protocol is presented, where rapid desalting in less than 15 minutes is achieved using miniaturized size-exclusion chromatography columns in pipette tips on an automated liquid handler. The peptide samples were analyzed using an electrospray ionization (ESI) orbitrap mass spectrometer coupled to an ultra-high-performance liquid chromatography (UHPLC) system with a dual column switching system. RESULTS: No significant change was observed in product attributes and their quantities compared with manual, low-artifact sample preparation. The sample recovery using the buffer exchange tips was greatly enhanced over the manual spin cartridges while still demonstrating excellent reproducibility for a wide variety of starting sample concentrations. Unlike a plate desalting system, the individual columns provide flexibility in the number of samples prepared at a time and sample locations within plates. CONCLUSIONS: This automated protocol enables the preparation of up to 96 samples with less "at-bench" time than the manual preparation of a smaller batch of samples, thereby greatly facilitating support of process development and the use of the MAM in quality control.

Factors Compromising Glucuronidase Performance in Urine Drug Testing Potentially Resulting in False Negatives.

Next generation ß-glucuronidases can effectively cleave glucuronides in urine at room temperature. However, during the discovery studies, additional challenges were identified for urine drug testing across biologically relevant pH extremes and patient urine specimens. Different enzymes were evaluated across clinical urine specimens and commercially available urine control matrices. Each enzyme shows distinct substrate preferences, pH optima, and variability across clinical specimens. These results demonstrate how reliance on a single glucuronidated substrate as the internal hydrolysis control cannot ensure performance across a broader panel of analytes. Moreover, sample specific urine properties compromise ß-glucuronidases to varying levels, more pronounced for some enzymes, and thereby lower the recovery of some drug analytes in an enzyme-specific manner. A minimum of 3-fold dilution of urine with buffer yields measurable improvements in achieving target pH and reducing the impact of endogenous compounds on enzyme performance. After subjecting the enzymes to pH extremes and compromising chemicals, one particular ß-glucuronidase was identified that addressed many of these challenges and greatly lower the risk of failed hydrolyses. In summary, we present strategies to evaluate glucuronidases that aid in higher accuracy urine drug tests with lower potential for false negatives.

Enhancing the multi-attribute method through an automated and high-throughput sample preparation.

The multi-attribute method (MAM), a recent advance in the application of liquid chromatography-mass spectrometry within the pharmaceutical industry, enables the simultaneous monitoring of multiple product quality attributes in a single analytical method. While MAM is coupled with automated data processing and reporting, the sample preparation, based on proteolytic peptide mapping, remains cumbersome and low throughput. The standard sample preparation for MAM relies on protein denaturation, reduction, and alkylation prior to proteolytic digestion, but often a desalting step is required to maintain enzymatic activity. While most of the sample preparation can be automated on a standard robotic liquid handling system, a streamlined approach for protein desalting and temperature modulation is required for a viable, fully automated digestion. In this work, for the first time, a complete tip-based MAM sample preparation is automated on a single robotic liquid handling system, leveraging a deck layout that integrates both heating and cooling functionalities. The fully automated method documented herein achieves a high-throughput sample preparation for MAM, while maintaining superior method performance.Abbreviations: MAM: multi-attribute method; PQAs: product quality attributes; CE: capillary electrophoresis; IEX: ion-exchange chromatography; HILIC-FLR: hydrophilic interaction liquid chromatography coupled to a fluorescence detector; RP-LC/UV: reversed-phase liquid chromatography coupled to a UV detector; MS: mass spectrometry; NPD: new peak detection; GdnHCl: guanidine hydrochloride; TIC: total ion current; pAb: polyclonal antibody; IgG: immunoglobulin G; DTT: dithiothreitol; IAA: iodoacetic acid; TFA: trifluoroacetic acid; A280: absorbance at 280 nm wavelength; 96MPH: 96-channel multi-probe head; CPAC: Cold Plate Air Cooled; HHS: Hamilton Heater Shaker; DWP: Deep-Well Plate; PCR: Polymerase Chain Reaction; NTR: Nested Tip Rack; Met: methionine; Trp: tryptophan; N-term pQ: N-terminal glutamine cyclization; Lys: lysine; PAM: peptidylglycine α-amidating monooxygenase; G0F: asialo-, agalacto-, bi-antennary, core substituted with fucose; G1F: asialo-, mono-galactosylated bi-antennary, core substituted with fucose; G2F: asialo-, bi-galactosylated bi-antennary, core substituted with fucose; G0: asialo-, agalacto-, bi-antennary; Man5: oligomannose 5; Man8: oligomannose 8; TriF: asialo-, tri-galactosylated tri-antennary, core substituted with fucose.

Variants of glycosyl hydrolase family 2 ß-glucuronidases have increased activity on recalcitrant substrates.

Glucuronidated drug metabolites can be quantified from urine samples by first hydrolyzing conjugates with ß-glucuronidase (ß-GUS) and then separating free drug molecules by liquid chromatography and mass spectrometry detection (LC-MS). To improve the activity and specificity of various ß-GUS, we designed enzyme chimeras and generated site-saturation variants based on structural analyses, then screened them for improved activity on drug metabolites important to clinical and forensic drug-testing laboratories. Often, an increase of activity on one substrate of interest was countered by loss of activity against another, and there was no strong correlation of activity on standard ß-glucuronidase substrates to activity on recalcitrant drug glucuronides. However, we discovered a chimera of two enzymes from different species of Aspergillus that displays a 27 % increase in activity on morphine-3-glucuronide than the parent proteins. Furthermore, mutations in the M-loop, which is a loop near the active site, resulted in numerous variants with dramatically increased rates of hydrolysis on drug glucuronides. Specifically, the M-loop variant Q451D/A452E of a ß-GUS from Brachyspira pilosicoli has a 50-fold and 25-fold increase in activity on the recalcitrant substrates codeine-6-glucuronide and dihydrocodeine-6-glucuronide, respectively, compared to the parent enzyme.

Purification, Characterization, and Structural Studies of a Sulfatase from Pedobacter yulinensis.

Sulfatases are ubiquitous enzymes that hydrolyze sulfate from sulfated organic substrates such as carbohydrates, steroids, and flavones. These enzymes can be exploited in the field of biotechnology to analyze sulfated metabolites in humans, such as steroids and drugs of abuse. Because genomic data far outstrip biochemical characterization, the analysis of sulfatases from published sequences can lead to the discovery of new and unique activities advantageous for biotechnological applications. We expressed and characterized a putative sulfatase (PyuS) from the bacterium Pedobacter yulinensis. PyuS contains the (C/S)XPXR sulfatase motif, where the Cys or Ser is post-translationally converted into a formylglycine residue (FGly). His-tagged PyuS was co-expressed in Escherichia coli with a formylglycine-generating enzyme (FGE) from Mycobacterium tuberculosis and purified. We obtained several crystal structures of PyuS, and the FGly modification was detected at the active site. The enzyme has sulfatase activity on aromatic sulfated substrates as well as phosphatase activity on some aromatic phosphates; however, PyuS did not have detectable activity on 17α-estradiol sulfate, cortisol 21-sulfate, or boldenone sulfate.

Parallel sample processing using dispersive INtip micro-purification on programmable multichannel pipettes.

Automation gives researchers the ability to process and screen orders of magnitude higher numbers of samples than manual experimentation. Current biomacromolecule separation methodologies suffer from necessary manual intervention, making their translation to high-throughput automation difficult. Herein, we present the first characterization of biomacromolecule affinity purification via dispersive solid-phase extraction in a pipette tip (INtip). We use commercially available resin and compare efficiency with batch and spin column methodologies. Moreover, we measure the kinetics of binding and evaluate resin binding capacities. INtip technology is effective on, and scalable for, an automated platform (INTEGRA ASSIST). The results suggest that high-throughput biomolecular workflows will benefit from the integration of INtip separations.

Automating Complex, Multistep Processes on a Single Robotic Platform to Generate Reproducible Phosphoproteomic Data.

Mass spectrometry-based phosphoproteomics holds promise for advancing drug treatment and disease diagnosis; however, its clinical translation has thus far been limited. This is in part due to an unstandardized and segmented sample preparation process that involves cell lysis, protein digestion, peptide desalting, and phosphopeptide enrichment. Automating this entire sample preparation process will be key in facilitating standardization and clinical translation of phosphoproteomics. While peptide desalting and phosphopeptide enrichment steps have been individually automated, integrating these two extractions and, further, the entire process requires more advanced robotic platforms as well as automation-friendly extraction tools. Here we describe a fully automated peptide desalting and phosphopeptide enrichment method using IMCStips on a Hamilton STAR. Using our established automated method, we identified more than 10,000 phosphopeptides from 200 µg of HCT116 cell lysate without fractionation with >85% phosphopeptide specificities. Compared with titania-based Spin Tip products, the automated IMCStips-based method gave 50% higher phosphopeptide identifications. The method reproducibility was further assessed using multiple reaction monitoring (MRM) to show >50% phosphopeptide recoveries after the automated phosphopeptide extraction with coefficients of variation (CVs) of <20% over a 3-week period. The established automated method is a step toward standardization of the sample preparation of phosphopeptide samples and could be further expanded upon to create a fully automated "cells to phosphopeptides" method.

Comparison of Purified ß-glucuronidases in Patient Urine Samples Indicates a Lack of Correlation Between Enzyme Activity and Drugs of Abuse Metabolite Hydrolysis Efficiencies Leading to Potential False Negatives.

Pain management laboratories analyze biological fluids (urine, saliva or blood) from patients treated for chronic pain to ensure compliance and to detect undisclosed drug use. The quantitation of multi-panel drugs in urine and tissues utilizes ß-glucuronidase to cleave the glucuronic acid and liberate the parent drug for mass spectrometry analysis. This work focuses on the comparison of three different, purified and commercially available ß-glucuronidases across 83 patient urine samples. One enzyme is genetically modified, expressed in bacteria and the other two enzymes are purified from abalone. The results indicate that the source of ß-glucuronidase plays an important role in substrate specificity which in turn dictates hydrolysis efficiency. Contaminants in the enzyme solutions also interfere with analyte detection. Altogether, these factors impact precision and accuracy of data interpretation, leading up to 13% positive/negative disagreement.

Increased activity of ß-glucuronidase variants produced by site-directed mutagenesis.

ß-glucuronidase (BGus) is an essential glycosyl hydrolase which has been widely used in biological and biomedical applications. In this paper, we report the construction and screening of nineteen Escherichia coli BGus (EBGus) mutants using site-directed mutagenesis. The mutants G559N, G559S and G559T showed a 3-5 fold increase in enzyme activity in comparison to wild type EBGus. In particular, G559S, with the highest activity, showed 2-6 fold enhanced activity compared to abalone and snail BGus extracts. Moreover, the glycine to serine mutagenesis for the same site in Staphylococcus sp. RLH1 BGus (StBGus) exhibited significantly enhanced activity, which indicated the importance of the G559→S mutation on BGus function. Based on this structural analysis, we postulate that the mutation at G559 plays an important role in the stabilization of the enzyme conformation, and thereby facilitates the effective binding of substrate.