Which functional group participates in the disulphide bond formation in proteins?

Options

A. Thiolactone
B. Thioether
C. Thiol
D. Thioester

Answer

C

Explanation

One property of thiols is that can be converted to disulphides by mild oxidizing agents.
`underset("Thiol")(2R-S-) Hoverset(overset([O])rarr)underset([H])larr underset("Disulphide")(R-S-S-R)`
This conversion can be reversed by mild reducing agents. The `-SH` group of cysteine makes cysteine a thiol. Cystine (present in most proteins) is synthesised from cysteine:
`2HO_(2)underset("Cysteine")underset(NH_(2))underset(|)(C)C CH_(2)SHoverset(overset([O])larr)underset([H])rarrHO_(2)Cunderset("Cystine")underset(NH_(2))underset(|)(C)HCH_(2)underset("linkage")underset("Disulphide")(S-SCH_(2))underset(NH_(2))underset(|)(C)HCO_(2)H`
Cysteine - cystine interconversion is used in permanent waving of hair.