Predicting Peptide Ionization Efficiencies for Electrospray Ionization Mass Spectrometry Using Machine Learning.

Mass spectrometry (MS) is inherently an information-rich technique. In this era of big data, label-free MS quantification for nontargeted studies has gained increasing popularity, especially for complex systems. One of the cornerstones of successful label-free quantification is the predictive modeling of ionization efficiency (IE) based on solutes' physicochemical properties.

Molecular architecture and platelet-activating properties of small immune complexes assembled on heparin and platelet factor 4.

Heparin-induced thrombocytopenia (HIT) is an adverse reaction to heparin leading to a reduction in circulating platelets with an increased risk of thrombosis. It is precipitated by polymerized immune complexes consisting of pathogenic antibodies that recognize a small chemokine platelet factor 4 (PF4) bound to heparin. Characterization of these immune complexes is extremely challenging due to the enormous structural heterogeneity of such macromolecular assemblies and their constituents.

Robust production of monovalent bispecific IgG antibodies through novel electrostatic steering mutations at the C1-C interface.

Bispecific antibodies represent an increasingly large fraction of biologics in therapeutic development due to their expanded scope in functional capabilities. Asymmetric monovalent bispecific IgGs (bsIgGs) have the additional advantage of maintaining a native antibody-like structure, which can provide favorable pharmacology and pharmacokinetic profiles. The production of correctly assembled asymmetric monovalent bsIgGs, however, is a complex engineering endeavor due to the propensity for non-cognate heavy and light chains to mis-pair.

Molecular architecture and platelet-activating properties of small immune complexes assembled on intact heparin and their possible involvement in heparin-induced thrombocytopenia.

Heparin-induced thrombocytopenia (HIT) is an adverse reaction to heparin leading to a reduction in circulating platelets with an increased risk of thrombosis. It is precipitated by polymerized immune complexes consisting of pathogenic antibodies that recognize a small chemokine platelet factor 4 (PF4) bound to heparin, which trigger platelet activation and a hypercoagulable state. Characterization of these immune complexes is extremely challenging due to the enormous structural heterogeneity of such macromolecular assemblies and their constituents (especially heparin).

Towards better understanding of the heparin role in NETosis: feasibility of using native mass spectrometry to monitor interactions of neutrophil elastase with heparin oligomers.

Neutrophil elastase is a serine protease released by neutrophils, and its dysregulation has been associated with a variety of debilitating pathologies, most notably cystic fibrosis. This protein is also a prominent component of the so-called neutrophil extracellular traps (NETs), whose formation is a part of the innate immunity response to invading pathogens, but also contributes to a variety of pathologies ranging from autoimmune disorders and inflammation to cancer to thrombotic complications in COVID-19. Retention of neutrophil elastase within NETs is provided by ejected DNA chains, although this protein is also capable of interacting with a range of other endogenous polyanions, such as heparin and heparan sulfate.

Charge Manipulation Using Solution and Gas-Phase Chemistry to Facilitate Analysis of Highly Heterogeneous Protein Complexes in Native Mass Spectrometry.

Structural heterogeneity is a significant challenge complicating (and in some cases making impossible) electrospray ionization mass spectrometry (ESI MS) analysis of noncovalent complexes comprising structurally heterogeneous biopolymers. The broad mass distribution exhibited by such species inevitably gives rise to overlapping ionic signals representing different charge states, resulting in a continuum spectrum with no discernible features that can be used to assign ionic charges and calculate their masses. This problem can be circumvented by using limited charge reduction, which utilizes gas-phase chemistry to induce charge-transfer reactions within ionic populations selected within narrow / windows, thereby producing well-defined and readily interpretable charge ladders.

Platelet Factor 4 Interactions with Short Heparin Oligomers: Implications for Folding and Assembly.

Association of platelet factor 4 (PF4) with heparin is a first step in formation of aggregates implicated in the development of heparin-induced thrombocytopenia (HIT), a potentially fatal immune disorder affecting 1-5% of patients receiving heparin. Despite being a critically important element in HIT etiology, relatively little is known about the specific molecular mechanism of PF4-heparin interactions. This work uses native mass spectrometry to investigate PF4 interactions with relatively short heparin chains (up to decasaccharides).

Ultrasonic Pretreatment Combined with Dry-State Glycation Reduced the Immunoglobulin E/Immunoglobulin G-Binding Ability of α-Lactalbumin Revealed by High-Resolution Mass Spectrometry.

Bovine α-lactalbumin (α-LA) is one of major food allergens in cow's milk. The present work sought to research the effects of ultrasonic pretreatment combined with dry heating-induced glycation between α-LA and galactose on the immunoglobulin E (IgE)/immunoglobulin G (IgG)-binding ability and glycation extent of α-LA, determined by inhibition enzyme-linked immunosorbent assay and high-resolution mass spectrometry, respectively. The IgE/IgG-binding ability of glycated α-LA was significantly decreased as a result of ultrasonic pretreatment, while the average molecular weight, incorporation ratio (IR) value, location and number of glycation sites, and degree of substitution per peptide (DSP) value were elevated.

The mechanism of reduced IgG/IgE-binding of β-lactoglobulin by pulsed electric field pretreatment combined with glycation revealed by ECD/FTICR-MS.

Bovine β-lactoglobulin (β-Lg) is a major allergen existing in milk and causes about 90% of IgE-mediated cow's milk allergies. Previous studies showed that pulsed electric field (PEF) treatment could partially unfold the protein, which may contribute to the improvement of protein glycation. In this study, the effect of PEF pretreatment combined with glycation on the IgG/IgE-binding ability and the structure of β-Lg was investigated.

Mechanism of Reduction in IgG and IgE Binding of β-Lactoglobulin Induced by Ultrasound Pretreatment Combined with Dry-State Glycation: A Study Using Conventional Spectrometry and High-Resolution Mass Spectrometry.

Bovine β-lactoglobulin (β-Lg) is one of major allergens in cow's milk. Previous study showed that ultrasound treatment induced the conformational changes of β-Lg and promoted the glycation in aqueous solutions, which is, however, less efficient compared with dry-state. In this work, the effect of ultrasound pretreatment combined with dry-state glycation on the IgG and IgE binding of β-Lg was studied.

Real-time monitoring of rolling circle amplification using aggregation-induced emission: applications in biological detection.

We report that QATPE, an aggregation-induced emission-active tetraphenylethene dye, can be used as a non-sequence-specific ssDNA probe for real-time monitoring of all rolling circle amplification (RCA) reactions, thus making RCA more suitable for biosensing applications.