scholarly journals Glycoproteomic measurement of site-specific polysialylation

2019 ◽  
Author(s):  
Ruby Pelingon ◽  
Cassandra L. Pegg ◽  
Lucia F. Zacchi ◽  
Toan K. Phung ◽  
Christopher B. Howard ◽  
...  
Keyword(s):  
Protein Function ◽  
Neurological Diseases ◽  
Polysialic Acid ◽  
Monosaccharide Composition ◽  
Degree Of Polymerization ◽  
Site Specific ◽  
Esi Ms ◽  
Therapeutic Drugs ◽  
Protease Digestion ◽  
Analytical Approaches

AbstractPolysialylation is the enzymatic addition of a highly negatively charged sialic acid polymer to the non-reducing termini of glycans. Polysialylation plays an important role in development, and is involved in neurological diseases, neural tissue regeneration, and cancer. Polysialic acid (PSA) is also a biodegradable and non-immunogenic conjugate to therapeutic drugs to improve their pharmacokinetics. PSA chains vary in length, composition, and linkages, while the specific sites of polysialylation are important determinants of protein function. However, PSA is difficult to analyse by mass spectrometry (MS) due to its high negative charge and size. Most analytical approaches for analysis of PSA measure its degree of polymerization and monosaccharide composition, but do not address the key questions of site specificity and occupancy. Here, we developed a high-throughput LC-ESI-MS/MS glycoproteomics method to measure site-specific polysialylation of glycoproteins. This method measures site-specific PSA modification by using mild acid hydrolysis to eliminate PSA and sialic acids while leaving the glycan backbone intact, together with protease digestion followed by LC-ESI-MS/MS glycopeptide detection. PSA-modified glycopeptides are not detectable by LC-ESI-MS/MS, but become detectable after desialylation, allowing measurement of site-specific PSA occupancy. This method is an efficient analytical workflow for the study of glycoprotein polysialylation in biological and therapeutic settings.Graphical Abstract

The challenge of detecting modifications on proteins

2020 ◽  
Vol 64 (1) ◽  
pp. 135-153 ◽  
Author(s):  
Lauren Elizabeth Smith ◽  
Adelina Rogowska-Wrzesinska
Keyword(s):  
Mass Spectrometry ◽  
Protein Function ◽  
Chemical Properties ◽  
Lysine Acetylation ◽  
Mass Determination ◽  
Post Translational Modifications ◽  
Site Specific ◽  
The Common

Abstract Post-translational modifications (PTMs) are integral to the regulation of protein function, characterising their role in this process is vital to understanding how cells work in both healthy and diseased states. Mass spectrometry (MS) facilitates the mass determination and sequencing of peptides, and thereby also the detection of site-specific PTMs. However, numerous challenges in this field continue to persist. The diverse chemical properties, low abundance, labile nature and instability of many PTMs, in combination with the more practical issues of compatibility with MS and bioinformatics challenges, contribute to the arduous nature of their analysis. In this review, we present an overview of the established MS-based approaches for analysing PTMs and the common complications associated with their investigation, including examples of specific challenges focusing on phosphorylation, lysine acetylation and redox modifications.

scholarly journals Molecular mechanisms of metabotropic GABAB receptor function

2021 ◽  
Vol 7 (22) ◽  
pp. eabg3362
Author(s):  
Hamidreza Shaye ◽  
Benjamin Stauch ◽  
Cornelius Gati ◽  
Vadim Cherezov
Keyword(s):  
G Protein ◽  
Molecular Mechanisms ◽  
Gabab Receptor ◽  
Neurological Diseases ◽  
Activation Mechanism ◽  
Allosteric Modulators ◽  
Inhibitory Neurotransmitter ◽  
Therapeutic Drugs ◽  
G Protein Coupled ◽  
The Brain

Metabotropic γ-aminobutyric acid G protein–coupled receptors (GABAB) represent one of the two main types of inhibitory neurotransmitter receptors in the brain. These receptors act both pre- and postsynaptically by modulating the transmission of neuronal signals and are involved in a range of neurological diseases, from alcohol addiction to epilepsy. A series of recent cryo-EM studies revealed critical details of the activation mechanism of GABAB. Structures are now available for the receptor bound to ligands with different modes of action, including antagonists, agonists, and positive allosteric modulators, and captured in different conformational states from the inactive apo to the fully active state bound to a G protein. These discoveries provide comprehensive insights into the activation of the GABAB receptor, which not only broaden our understanding of its structure, pharmacology, and physiological effects but also will ultimately facilitate the discovery of new therapeutic drugs and neuromodulators.

scholarly journals Anodic Titanium Dioxide Nanotubes for Magnetically Guided Therapeutic Delivery

2019 ◽  
Vol 9 (1) ◽  
Author(s):  
Morteza Hasanzadeh Kafshgari ◽  
Delf Kah ◽  
Anca Mazare ◽  
Nhat Truong Nguyen ◽  
Monica Distaso ◽  
...  
Keyword(s):  
Titanium Dioxide ◽  
Iron Oxide ◽  
Iron Oxide Nanoparticles ◽  
Hela Cells ◽  
Release Kinetics ◽  
Drug Loading ◽  
Oxide Nanoparticles ◽  
Site Specific ◽  
Therapeutic Drugs ◽  
Wide Range

Abstract Hollow titanium dioxide (TiO2) nanotubes offer substantially higher drug loading capacity and slower drug release kinetics compared to solid drug nanocarriers of comparable size. In this report, we load TiO2 nanotubes with iron oxide nanoparticles to facilitate site-specific magnetic guidance and drug delivery. We generate magnetic TiO2 nanotubes (TiO2NTs) by incorporating a ferrofluid containing Ø ≈ 10 nm iron oxide nanoparticles in planar sheets of weakly connected TiO2 nanotubes. After thermal annealing, the magnetic tubular arrays are loaded with therapeutic drugs and then sonicated to separate the nanotubes. We demonstrate that magnetic TiO2NTs are non-toxic for HeLa cells at therapeutic concentrations (≤200 µg/mL). Adhesion and endocytosis of magnetic nanotubes to a layer of HeLa cells are increased in the presence of a magnetic gradient field. As a proof-of-concept, we load the nanotubes with the topoisomerase inhibitor camptothecin and achieve a 90% killing efficiency. We also load the nanotubes with oligonucleotides for cell transfection and achieve 100% cellular uptake efficiency. Our results demonstrate the potential of magnetic TiO2NTs for a wide range of biomedical applications, including site-specific delivery of therapeutic drugs.

scholarly journals Site-specific monoubiquitination activates Ras by impeding GTPase-activating protein function

Small GTPases ◽  
2013 ◽  
Vol 4 (3) ◽  
pp. 186-192 ◽  
Author(s):  
G Aaron Hobbs ◽  
Harsha P Gunawardena ◽  
Rachael Baker ◽  
Xian Chen ◽  
Sharon L Campbell
Keyword(s):  
Protein Function ◽  
Gtpase Activating Protein ◽  
Site Specific

scholarly journals An Overview of Structural Aspects and Health Beneficial Effects of Antioxidant Oligosaccharides

2020 ◽  
Vol 26 (16) ◽  
pp. 1759-1777 ◽  
Author(s):  
Tatiane F. Vieira ◽  
Rúbia C. G. Corrêa ◽  
Rosely A. Peralta ◽  
Regina F. Peralta-Muniz-Moreira ◽  
Adelar Bracht ◽  
...  
Keyword(s):  
Antioxidant Activity ◽  
Antioxidant Activities ◽  
Sugar Content ◽  
Animal Health ◽  
Monosaccharide Composition ◽  
Degree Of Polymerization ◽  
Chemical Diversity ◽  
In Vivo Studies

Background: Non-digestible oligosaccharides are versatile sources of chemical diversity, well known for their prebiotic actions, found naturally in plants or produced by chemical or enzymatic synthesis or by hydrolysis of polysaccharides. Compared to polyphenols or even polysaccharides, the antioxidant potential of oligosaccharides is still unexplored. The aim of the present work was to provide an up-to-date, broad and critical contribution on the topic of antioxidant oligosaccharides. Methods: The search was performed by crossing the words oligosaccharides and antioxidant. Whenever possible, attempts at establishing correlations between chemical structure and antioxidant activity were undertaken. Results: The most representative in vitro and in vivo studies were compiled in two tables. Chitooligosaccharides and xylooligosaccharides and their derivatives were the most studied up to now. The antioxidant activities of oligosaccharides depend on the degree of polymerization and the method used for depolymerization. Other factors influencing the antioxidant strength are solubility, monosaccharide composition, the type of glycosidic linkages of the side chains, molecular weight, reducing sugar content, the presence of phenolic groups such as ferulic acid, and the presence of uronic acid, among others. Modification of the antioxidant capacity of oligosaccharides has been achieved by adding diverse organic groups to their structures, thus increasing also the spectrum of potentially useful molecules. Conclusion: A great amount of high-quality evidence has been accumulating during the last decade in support of a meaningful antioxidant activity of oligosaccharides and derivatives. Ingestion of antioxidant oligosaccharides can be visualized as beneficial to human and animal health.

Safety and Efficacy of Fremanezumab for the Prevention of Migraine: a Meta-analysis from Random Clinical Trails

2020 ◽  
Author(s):  
Bixi Gao ◽  
Nan Sun ◽  
Yanbo Yang ◽  
Yue Sun ◽  
Mingjia Chen ◽  
...  
Keyword(s):  
Adverse Events ◽  
Neurological Diseases ◽  
Meta Analysis ◽  
Cochrane Library ◽  
Serious Adverse Events ◽  
Safety And Efficacy ◽  
Therapeutic Drugs ◽  
Primary Endpoints ◽  
Calcitonin Gene ◽  
Clinical Trails

Abstract Background Fremanezumab (TEV-48125) is a fully humanized immunoglobulin G isotype 2a selective monoclonal antibody that potently binds to calcitonin gene-related peptide (CGRP). It is one of novel therapeutic drugs for the prevention of migraine, which is one of the most common neurological diseases worldwide. Several clinical trails have been conducted to investigate the safety and efficacy of fremanezumab, but there is no systematic review of existing literature has been performed. Hence, we performed a meta-analysis to investigate the efficacy and safety of fremanezumab for prevention of migraine. Method Pubmed (MEDLINE), Embase, and Cochrane Library were searched from January 2001 to August 2019 for randomized controlled trials (RCTs). Five RCTs with 3379 patients were finally included in our study. Result We pooled 3379 patients from 5 RCTs, the primary endpoints were mean monthly migraine and headache days, baseline to week 12. We found that fremanezumab led to a significant reduction in migraine days (P < 0.0001) and headache days (P < 0.0001) during 12 weeks compared with placebo. In addition, after using fremanezumab, the risk of at least one adverse event (P=0.001) or related to the trail regimen (P=0.0005) significantly increase compared with placebo. Conclusions Fremanezumab has good efficacy for the prevention of migraine. The administration of fremanezumab can cause some mild adverse events but not serious adverse events.

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