scholarly journals Optimization and kinetic modeling of interchain disulfide bond reoxidation of monoclonal antibodies in bioprocesses

mAbs ◽  
2020 ◽  
Vol 12 (1) ◽  
pp. 1829336
Author(s):  
Peifeng Tang ◽  
Zhijun Tan ◽  
Vivekh Ehamparanathan ◽  
Tingwei Ren ◽  
Laurel Hoffman ◽  
...  
2018 ◽  
Vol 19 (11) ◽  
pp. 3376 ◽  
Author(s):  
Natalia A. Koubassova ◽  
Sergey Y. Bershitsky ◽  
Andrey K. Tsaturyan

Tropomyosin (Tpm) is a coiled-coil actin-binding dimer protein that participates in the regulation of muscle contraction. Both Tpm chains contain Cys190 residues which are normally in the reduced state, but form an interchain disulfide bond in failing heart. Changes in structural and functional properties of Tpm and its complexes with actin upon disulfide cross-linking were studied using various experimental methods. To understand the molecular mechanism underlying these changes and to reveal the possible mechanism of the involvement of the cross-linking in heart failure, molecular dynamics (MD) simulations of the middle part of Tpm were performed in cross-linked and reduced states. The cross-linking increased bending stiffness of Tpm assessed from MD trajectories at 27 °C in agreement with previous experimental observations. However, at 40 °C, the cross-linking caused a decrease in Tpm stiffness and a significant reduction in the number of main chain hydrogen bonds in the vicinity of residues 133 and 134. These data are in line with observations showing enhanced thermal unfolding of the least stable part of Tpm at 30–40 °C and accelerated trypsin cleavage at residue 133 at 40 °C (but not at 27 °C) upon cross-linking. These results allow us to speculate about the possible mechanism of involvement of Tpm cross-linking to heart failure pathogenesis.


2008 ◽  
Vol 149 (1) ◽  
pp. 412-423 ◽  
Author(s):  
Alessio Lombardi ◽  
Alessandra Barbante ◽  
Pietro Della Cristina ◽  
Daniele Rosiello ◽  
Chiara Lara Castellazzi ◽  
...  

Blood ◽  
2007 ◽  
Vol 110 (11) ◽  
pp. 2706-2706
Author(s):  
Wenman Wu ◽  
Dipali Sinha ◽  
James D. Lear ◽  
Paul C. Billings ◽  
Peter N. Walsh

Abstract Factor XI (FXI), a coagulation protein essential for normal hemostasis, is a homodimer consisting of two identical subunits of 80 KDa linked by a disulfide bond formed by Cys321 within the Apple 4 (A4) domain of each subunit. Prekallikrein (PK), in spite of its high homology with FXI both in amino acid sequence and domain structure, is a monomer. Cys321 in PK forms an intrachain disulfide bond with Cys326. However FXI/C321S (in which interchain disulfide bond formation is precluded) is a noncovalent dimer. Thus, there are interacting residues between the two subunits of FXI that are responsible for mediating its unique homodimeric structure. Examination of the crystal structure of FXI (Papagrigoriou E, McEwan P, Walsh PN, Emsley J. Nature Structural & Molecular Biology. 2006;13:557–8) shows salt bridges between Lys331 of one subunit with Glu287 of the other subunit as well as hydrophobic interactions at the interface of the A4 domains involving Ile290, Leu284 and Tyr329. FXI/C321S, FXI/C321S/K331A, FXI/C321S/E287A, FXI/C321S/I290A, FXI/C321S/Y329A, FXI/C321S/L284A and FXI/C321S/K331R were expressed in HEK293 cells and characterized using size exclusion chromatography (SEC), analytical ultracentrifugation (AUC), and functional assays. Whereas FXI/C321S existed in a monomer/dimer equilibrium (Kd ∼40 nM) all other mutants were predominantly monomers by SEC with impaired dimer formation by AUC (Kd 3.4–38 μM). All the monomeric mutants when converted to the active enzyme, FXIa, were able to hydrolyze the small chromogenic substrate S-2366 with normal values of Km and Vmax and cleaved the macromolecular substrate FIX at both its scissile bonds at rates similar to those observed with wtFXIa strongly suggesting that all mutant proteins were properly folded. However all the monomeric mutants displayed impaired clotting activity in an APTT assay and displayed markedly decreased rates of activation by FXIIa or thrombin and autoactivation in the presence or absence of dextran sulfate. We conclude that salt bridges formed between Lys331 of one subunit and Glu287 of the other together with hydrophobic interactions of residues Ile290 with Leu284 and Tyr329 with Tyr329 and are essential for normal homodimer formation, which is essential for normal proteolytic activation of FXI by FXIIa, thrombin and FXIa either in solution or on an anionic surface.


2015 ◽  
Vol 83 (7) ◽  
pp. 2714-2724 ◽  
Author(s):  
Madison Zuverink ◽  
Chen Chen ◽  
Amanda Przedpelski ◽  
Faith C. Blum ◽  
Joseph T. Barbieri

Botulinum neurotoxins (BoNTs) and tetanus toxin (TeNT) are the most potent toxins for humans and elicit unique pathologies due to their ability to traffic within motor neurons. BoNTs act locally within motor neurons to elicit flaccid paralysis, while retrograde TeNT traffics to inhibitory neurons within the central nervous system (CNS) to elicit spastic paralysis. BoNT and TeNT are dichain proteins linked by an interchain disulfide bond comprised of an N-terminal catalytic light chain (LC) and a C-terminal heavy chain (HC) that encodes an LC translocation domain (HCT) and a receptor-binding domain (HCR). LC translocation is the least understood property of toxin action, but it involves low pH, proteolysis, and an intact interchain disulfide bridge. Recently, Pirazzini et al. (FEBS Lett 587:150–155, 2013,http://dx.doi.org/10.1016/j.febslet.2012.11.007) observed that inhibitors of thioredoxin reductase (TrxR) blocked TeNT and BoNT action in cerebellar granular neurons. In the current study, an atoxic TeNT LC translocation reporter was engineered by fusing β-lactamase to the N terminus of TeNT [βlac-TeNT(RY)] to investigate LC translocation in primary cortical neurons and Neuro-2a cells. βlac-TeNT(RY) retained the interchain disulfide bond, showed ganglioside-dependent binding to neurons, required acidification to promote βlac translocation, and was sensitive to auranofin, an inhibitor of thioredoxin reductase. Mutation of βlac-TeNT(RY) at C439S and C467S eliminated the interchain disulfide bond and inhibited βlac translocation. These data support the requirement of an intact interchain disulfide for LC translocation and imply that disulfide reduction is a prerequisite for LC delivery into the host cytosol. The data also support a model that LC translocation proceeds from the C to the N terminus. βlac-TeNT(RY) is the first reporter system to measure translocation by an AB single-chain toxin in intact cells.


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