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Intramolecular general acid catalysis in the binding reactions of alpha 2-macroglobulin and complement components C3 and C4

Authors :
Davies, SG
Sim, RB
Publication Year :
2016
Publisher :
Kluwer Academic Publishers, 2016.

Abstract

The complement system proteins C3 and C4 and the plasma protease inhibitor alpha 2-macroglobulin, when activated by limited proteolysis, can bind covalently to other macromolecules. The three proteins also exhibit an unusual internal peptide-bond cleavage reaction when denatured. The covalent binding reaction is likely to occur by a transacylation mechanism involving an internal thiolester in the three proteins. However, the activated species of these proteins are much more reactive than simple thiolesters. Studies of molecular models of the thiolester region in C3 show that an intramolecular acid catalysis mechanism can both account for the exceptional reactivity of the activated form of these proteins and provide an explanation for the denaturation-induced peptide bond cleavage.

Details

Language :
English
Database :
OpenAIRE
Accession number :
edsair.dedup.wf.001..7523975f2f8e53c92356be983f8718fe
Full Text :
https://doi.org/10.1007/bf01121579