A $- \mathrm { OH }$ B
C $- \mathrm { NH } _ { 2 }$

Multiple Choice

A. $- \mathrm { OH }$
B.
C. $- \mathrm { NH } _ { 2 }$
D. $- \mathrm { SH }$
- Which of the functional groups shown helps stabilise proteins by forming covalent cross-links within or between protein molecules?

A) A
B) B
C) C
D) D