Question

The ability of C3 and C4 to covalently bind to microbial surfaces is due to the presence of a highly reactive _____ bond that gets exposed upon _______ of the molecule.

a) Ionic; Hydrolysis
b) Peptide; Glycosylation
c) Ester; Phosphorylation
d) Thioester; Cleavage

Answer 1

The highly reactive bond that allows C3 and C4 to bind to microbial surfaces upon cleavage of the molecule is a thioester bond.

Step-by-step explanation:

The ability of C3 and C4 to covalently bind to microbial surfaces is due to the presence of a highly reactive thioester bond that gets exposed upon cleavage of the molecule. Upon activation, the C3 protein splits into fragments. The larger fragment, C3b, can bind to pathogen surfaces, and the exposure of the thioester bond is crucial for this attachment, initiating a cascade of events that lead to the destruction of the pathogen via the complement system.