Reactivity-driven cleanup of 2-Aminobenzamide derivatized oligosaccharides

Engineered short forms of perlecan enhance angiogenesis by potentiating growth factor signalling

Growth factors are key molecules involved in angiogenesis, a process critical for tissue repair and regeneration. Despite the potential of growth factor delivery to stimulate angiogenesis, limited clinical success has been achieved with this approach. Growth factors interact with the extracellular matrix (ECM), and particularly heparan sulphate (HS), to bind and potentiate their signalling. Here we show that engineered short forms of perlecan, the major HS proteoglycan of the vascular ECM, bind and signal angiogenic growth factors, including fibroblast growth factor 2 and vascular endothelial growth factor-A. We also show that engineered short forms of perlecan delivered in porous chitosan biomaterial scaffolds promote angiogenesis in a rat full thickness dermal wound model, with the fusion of perlecan domains I and V leading to superior vascularisation compared to native endothelial perlecan or chitosan scaffolds alone. Together, this study demonstrates the potential of engineered short forms of perlecan delivered in chitosan scaffolds as next generation angiogenic therapies which exert biological activity via the potentiation of growth factors.

Analysis of carbohydrates and glycoconjugates by matrix-assisted laser desorption/ionization mass spectrometry: An update for 2017-2018

This review is the tenth update of the original article published in 1999 on the application of matrix-assisted laser desorption/ionization mass spectrometry (MALDI) mass spectrometry to the analysis of carbohydrates and glycoconjugates and brings coverage of the literature to the end of 2018. Also included are papers that describe methods appropriate to glycan and glycoprotein analysis by MALDI, such as sample preparation techniques, even though the ionization method is not MALDI. Topics covered in the first part of the review include general aspects such as theory of the MALDI process, new methods, matrices, derivatization, MALDI imaging, fragmentation and the use of arrays. The second part of the review is devoted to applications to various structural types such as oligo- and poly-saccharides, glycoproteins, glycolipids, glycosides, and biopharmaceuticals. Most of the applications are presented in tabular form. The third part of the review covers medical and industrial applications of the technique, studies of enzyme reactions, and applications to chemical synthesis. The reported work shows increasing use of combined new techniques such as ion mobility and highlights the impact that MALDI imaging is having across a range of diciplines. MALDI is still an ideal technique for carbohydrate analysis and advancements in the technique and the range of applications continue steady progress.

Integrated Process Analytical Platform for Automated Monitoring of Monoclonal Antibody N-Linked Glycosylation

The biopharmaceutical industry is transitioning toward the adoption of continuous biomanufacturing practices that are often more flexible and efficient than traditional batch processes. Federal regulatory agencies are further urging the use of advanced process analytical technology (PAT) to analyze the design space to increase the process knowledge and enable high-quality biologic production. Post-translational modifications of proteins, such as N-linked glycosylation, are often critical quality attributes that affect biologics' safety and efficacy, requiring close monitoring during manufacturing. Here, we developed an online sequential-injection-based PAT system, called N-GLYcanyzer, which can rapidly monitor mAb glycosylation during upstream biomanufacturing. The key innovation includes the design of an integrated mAb sampling and fully automated sample derivation system for antibody titer and glycoform analysis within 3 h. The N-GLYcanyzer process includes mAb capture, deglycosylation, released glycan labeling with fluorescent dyes, and labeled glycan enrichment for direct injection/analysis on an integrated high-performance liquid chromatography system. Different fluorescent tags and reductants were tested to maximize glycan labeling efficiency under aqueous conditions, while porous graphitized carbon (PGC) was used for optimizing glycan recovery and enrichment. We found that 2-aminobenzamide labeling of glycans with 2-picoline borane as a reducing agent, using the N-GLYcanyzer workflow, shows higher glycan labeling efficiency under aqueous conditions, leading upward to a 5-fold increase in fluorescent product intensity. Finally, we showcase how the N-GLYcanyzer platform can be implemented at-/online in an upstream bioreactor for automated and near-real-time glycosylation monitoring of a Trastuzumab biosimilar produced by Chinese hamster ovary cells.

Occurrence of a D-arabinose-containing complex-type free-N-glycan in the urine of cancer patients

Urinary free-glycans are promising markers of disease. In this study, we attempted to identify novel tumor markers by focusing on neutral free-glycans in urine. Free-glycans extracted from the urine of normal subjects and cancer patients with gastric, colorectal, pancreatic and bile duct were fluorescently labeled with 2-aminopyridine. Profiles of these neutral free-glycans constructed using multidimensional high performance liquid chromatography separation were compared between normal controls and cancer patients. The analysis identified one glycan in the urine of cancer patients with a unique structure, which included a pentose residue. To reveal the glycan structure, the linkage fashion, monosaccharide species and enantiomer of the pentose were analyzed by high performance liquid chromatography and mass spectrometry combined with several chemical treatments. The backbone of the glycan was a monoantennary complex-type free-N-glycan containing β1,4-branch. The pentose residue was attached to the antennal GlcNAc and released by α1,3/4-l-fucosidase. Intriguingly, the pentose residue was consistent with d-arabinose. Collectively, this glycan structure was determined to be Galβ1-4(d-Araβ1-3)GlcNAcβ1-4Manα1-3Manβ1-4GlcNAc-PA. Elevation of d-arabinose-containing free-glycans in the urine of cancer patients was confirmed by selected reaction monitoring. This is the first study to unequivocally show the occurrence of a d-arabinose-containing oligosaccharide in human together with its detailed structure.

Long-term intrathecal administration of morphine vs. baclofen: Differences in CSF glycoconjugate profiles using multiglycomics

Opioid use for treatment of persistent pain has increased dramatically over the past two decades, but it has not resulted in improved pain management outcomes. To understand the molecular mechanisms of opioids, molecular signatures that arise from opioid exposure are often sought after, using various analytical methods. In this study, we performed proteomics, and multiglycomics via sequential analysis of polysialic acids, glycosaminoglycans, N-glycans and O-glycans, using the same cerebral spinal fluid (CSF) sample from patients that had long-term (>2 years), intrathecal morphine or baclofen administered via an indwelling pump. Proteomics and N-glycomics signatures between the two treatment groups were highly conserved, while significant differences were observed in polysialic acid, heparan sulfate glycosaminoglycan and O-glycan profiles between the two treatment groups. This represents the first study to investigate the potential relationships between diverse CSF conjugated glycans and long-term intrathecal drug exposure. The unique changes, observed by a sequential analytical workflow, reflect previously undescribed molecular effects of opioid administration and pain management.

Recent developments in sample preparation techniques combined with high-performance liquid chromatography: A critical review

This review article compares and contrasts sample preparation techniques coupled with high-performance liquid chromatography (HPLC) and describes applications developed in biomedical, forensics, and environmental/industrial hygiene in the last two decades. The proper sample preparation technique can offer valued data for a targeted application when coupled to HPLC and a suitable detector. Improvements in sample preparation techniques in the last two decades have resulted in efficient extraction, cleanup, and preconcentration in a single step, thus providing a pathway to tackle complex matrix applications. Applications such as biological therapeutics, proteomics, lipidomics, metabolomics, environmental/industrial hygiene, forensics, glycan cleanup, etc., have been significantly enhanced due to improved sample preparation techniques. This review looks at the early sample preparation techniques. Further, it describes eight sample preparation technique coupled to HPLC that has gained prominence in the last two decades. They are (1) solid-phase extraction (SPE), (2) liquid-liquid extraction (LLE), (3) gel permeation chromatography (GPC), (4) Quick Easy Cheap Effective Rugged, Safe (QuEChERS), (5) solid-phase microextraction (SPME), (6) ultrasonic-assisted solvent extraction (UASE), and (7) microwave-assisted solvent extraction (MWASE). SPE, LLE, GPC, QuEChERS, and SPME can be used offline and online with HPLC. UASE and MWASE can be used offline with HPLC but have also been combined with the online automated techniques of SPE, LLE, GPC, or QuEChERS for targeted analysis. Three application areas of biomedical, forensics, and environmental/industrial hygiene are reviewed for the eight sample preparation techniques. Three hundred and twenty references on the eight sample preparation techniques published over the last two decades (2001-2021) are provided. Other older references were included to illustrate the historical development of sample preparation techniques.

So You Discovered a Potential Glycan-Based Biomarker; Now What? We Developed a High-Throughput Method for Quantitative Clinical Glycan Biomarker Validation

Glycomic-based approaches to discover potential biomarkers have shown great promise in their ability to distinguish between healthy and diseased individuals; these methods can identify when aberrant glycosylation is significant, but they cannot practically be adapted into widely implemented diagnostic assays because they are too complex, expensive, and low-throughput. We have developed a new strategy that addresses challenges associated with sample preparation, sample throughput, instrumentation needs, and data analysis to transfer the valuable knowledge provided by protein glycosylation into a clinical environment. Notably, the detection limits of the assay are in the single-digit picomole range. Proof of principle is demonstrated by quantifying the changes in the sialic acid content in fetuin. As the sialic acid content in proteins varies in a number of disease states, this example demonstrates the utility of the method for biomarker analysis. Furthermore, the developed method can be adapted to other biologically important saccharides, affording a broad array of quantitative glycomic analyses that are accessible in a high-throughput, plate-reader format. These studies enable glycomic-based biomarker discovery efforts to transition through the difficult landscape of developing a potential biomarker into a clinical assay.

Mass spectrometry-based qualitative and quantitative N-glycomics: An update of 2017-2018

N-glycosylation is one of the most frequently occurring protein post-translational modifications (PTMs) with broad cellular, physiological and pathological relevance. Mass spectrometry-based N-glycomics has become the state-of-the-art instrumental analytical pipeline for sensitive, high-throughput and comprehensive characterization of N-glycans and N-glycomes. Improvement and new development of methods in N-glycan release, enrichment, derivatization, isotopic labeling, separation, ionization, MS, tandem MS and informatics accompany side-by-side wider and deeper application. This review provides a comprehensive update of mass spectrometry-based qualitative and quantitative N-glycomics in the years of 2017-2018.

Properties of arabinogalactan-proteins in European pear (Pyrus communis L.) fruits

Arabinogalactans (AGs) and arabinogalactan-proteins (AGPs) were partially purified from an extract of fruits of the European pear (Pyrus communis L.) by DEAE-cellulose ion-exchange and Sepharose 6B gel-filtration chromatography. Among 7 AG(P)-containing fractions, a neutral AGP (SE-1) was confirmed to be highly purified (M_r 67,000) and rich in L-Ara and Gal; this fraction included a small amount (2.6%, w/w) of protein and showed the highest reactivity forming precipitate with β-Glc Yariv reagent among the 7 fractions, the intensity of which was comparable to that of gum arabic, a standard AGP. Another accompanying minor low-M_r neutral AGP (SE-2; M_r approx. 7200) still contained other polysaccharide (starch fragments) and did not show Yariv reactivity. The carbohydrate moieties of SE-1 consisted of consecutive (1 → 3)-linked β-galactosyl backbone chains substituted with side chains of (1 → 6)-linked β-galactosyl residues at O-6, to which mainly single α-l-arabinofuranosyl residues were attached through O-3. This structural feature was also observed for SE-2. Successive digestion of SE-1 with α-l-arabinofuranosidase and exo-β-(1 → 3)-galactanase with the aid of endo-β-(1 → 3)-galactanase released most (more than 98%, w/w) of the carbohydrate moieties as low-M_r fragments. These consisted of free L-Ara and Gal, and a series of β-(1 → 6)-galactooligosaccharides with degree of polymerization (dp) up to at least 17, indicative of attachment of (1 → 6)-linked β-galactosyl side chains of varying length along the (1 → 3)-linked β-galactosyl backbone chains.

Development of a colorimetric PNGase activity assay

PNGases are crucial targets and valuable tools in analyzing asparagine-linked carbohydrate moieties (N-glycans) of glycoproteins. Activity tests of PNGases have been little improved since their discovery four decades ago, and still rely on observing deglycosylation patterns of glycoproteins or glycopeptides using SDS-PAGE or HPLC analysis. These techniques cannot be easily adapted for automated sampling and high-throughput procedures. Herein, we describe a PNGase activity assay which relies on the conversion of WST-1, a yellowish, water-soluble tetrazolium dye (sodium 2-(4-Iodophenyl)-3-(4-nitro-phenyl)-5-(2,4-disulfophenyl)-2H-tetrazolate), into a blue formazan dye. In this work, we showed that WST-1 could be reduced by N-glycans, which were enzymatically released from glycoprotein substrates. After optimization of the assay conditions, the robustness of the method was challenged by quantifying the activity of various PNGase isoforms at different purification stages using a microwell plate reader. Furthermore, the assay could be used to obtain steady-state kinetics of PNGase H⁺ wild-type and mutant variants, which showed significant differences in their enzymatic reaction rates. The simplicity and robustness of this method might be of benefit for the detection of PNGase activity in routine applications of large amounts of samples.