Flexible transmembrane helices frequently support the conformational transitions between different functional states of membrane proteins. While proline is well known to distort and destabilize transmembrane helices, the role of glycine is still debated. Here, we systematically investigated the effect of glycine on transmembrane helix flexibility by placing it at different sites within the otherwise uniform leucine/valine repeat sequence of the LV16 model helix. We show that amide deuterium/hydrogen exchange kinetics are increased near glycine. Molecular dynamics simulations reproduce the measured exchange kinetics and reveal, at atomic resolution, a severe packing defect at glycine that enhances local hydration. Furthermore, glycine alters H-bond occupancies and triggers a redistribution of α-helical and 3-helical H-bonds. These effects facilitate local helix bending at the glycine site and change the collective dynamics of the helix.
The aim of this study was to characterize the product variants of a therapeutic T-cell bispecific humanized monoclonal antibody (TCB Mab, ∼200 kDa, asymmetric) and to develop an online cation-exchange chromatography native electrospray mass spectrometry method (CEC-UV-MS) for direct TCB Mab charge variant monitoring during bioprocess and formulation development. For the identification and functional evaluation of the diverse and complex TCB Mab charge variants, offline fractionation combined with comprehensive analytical testing was applied. The offline fractionation of abundant product variant peaks enabled identification of coeluting acid charge variants such as asparagine deamidation, primary and secondary Fab glycosylation (with and without sialic acid), and the presence of O-glycosylation in the G4S-linker region. Consequently, a new nonconsensus N-glycosylation motif (N-338-FG) in the heavy chain CDR region was discovered. Functional evaluation by cellbased potency testing demonstrated a clear and negative impact of both asparagine deamidations, whereas the O-glycosylation did not affect the TCB Mab biological activity. We established an online native CEC-UV-MS method, with an ammonium acetate buffer and pH gradient, to directly monitor the TCB Mab charge variants. All abundant chemical degradations and post-translational amino acid modifications already identified by offline fraction experiments and liquid chromatography mass spectrometry peptide mapping could also be monitored by the online CEC-UV-MS method. The herein reported online native CEC-UV-MS methodology represents a complementary or even alternative approach for multiattribute monitoring of biologics, offering multiple benefits, including increased throughput and reduced sample handling and intact protein information in the near-native state.
Aim: Fragment crystallizable (Fc) glycosylation of immunoglobulin G-type monoclonal antibodies applied to therapeutic applications is regarded a critical quality attribute and can influence bioactivity, pharmacokinetics and/or immunogenicity/safety. Investigating the impact of certain Fc N-glycans is therefore of importance to assess its criticality for a therapeutic product. This has been done for N-glycan types like fucosylation, galactosylation or sialylation. There were contradictory results reported for functionality especially with regard to sialylation. Material & methods: We elucidated the effect of terminal sialic acid residues on Fcγ receptor binding and antibody dependent cytotoxicity activity of two immunoglobulin G1 antibodies with different levels of fucosylation/bi-secting. Conclusion: We found the impact to be specific to the sialylation linkage type, in other words, α2,3- versus α2,6-linked sialic acid attached to the terminal galactose residues
A randomized, double-blind trial compared treatment with the immune modulator WF10 (ten patients) and placebo (nine patients) administered in cycles over 3 months among individuals with advanced AIDS. There were no notable clinical adverse events; changes in hematologic and chemistry values were comparable in the two groups. In both groups, median HIV-RNA PCR values remained stable. Immunologic variables showed a consistent tendency to increase in the WF10 group and to decrease in the control group, with significant differences between groups for median WBC, lymphocyte, CD19, and CD35 values. Ten infections occurred in the control group, four of which were Pneumocystis carinii pneumonia (PCP), and three in the WF10 group none of which was PCP. Five patients in the control group were hospitalized during the trial for a total of 53 days; no patients in the WF10 group were hospitalized. Over a subsequent 9-months follow-up, six patients from the control group and one from the WF10 group died. These results indicate that WF10 administration appears safe, may enhance immunologic function, and unlike other macrophage-activating cytokines does not increase HIV expression in this patient population. Further studies of WF10 in larger patient populations are warranted.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.
hi@scite.ai
10624 S. Eastern Ave., Ste. A-614
Henderson, NV 89052, USA
Copyright © 2024 scite LLC. All rights reserved.
Made with 💙 for researchers
Part of the Research Solutions Family.