LIFE SCIENCE

Detailed explanation-1: -The formation of a disulfide bond by two side chain S atoms of spatially proximal cysteines constitutes a two-electron oxidation process leading from reduced sulfhydryl groups of cysteines (S-H) to the oxidized cystine (S-S) residue.

Detailed explanation-2: -The oxidation of cysteines to form disulphide bonds is catalysed rapidly in both the ER and periplasmic space by several different thiol-disulphide oxidoreductases, including PDI.

Detailed explanation-3: -Disulfide bonds are covalent interactions formed between the sulfur atoms of two cysteine residues. As structural bonds in proteins, disulfide bonds stabilize monomeric and multisubunit proteins [1] constituting the only natural covalent link between polypeptide strands.

Detailed explanation-4: -The formation of disulfide bonds between cysteine residues occurs during the folding of many proteins that enter the secretory pathway. As the polypeptide chain collapses, cysteines brought into proximity can form covalent linkages during a process catalyzed by members of the protein disulfide isomerase family.

Detailed explanation-5: -Covalent disulfide bonds formed between two cysteine residues contribute another fundamental type of linkage, providing more stability and selectivity than noncovalent interactions.