Antibody Structure Problem Set

Problem 5. Antibody/antigen binding

Tutorial to help answer the question

Glutamine 121 protrudes away from the surface of the antigen. The exposed residue can fit into a depression in the antibody. Association leads to the formation of __________ between antigen and antibody?

A.	covalent bonds
B.	ionic bonds
C.	hydrophobic attractions
D.	hydrogen bonds

Tutorial

Multiple weak interactions between the antibody and antigen create a strong binding affinity. The orientation of the antibody's amino acids maximizes hydrogen bonding between the antigen and the antibody.

Gln 121 (green) fits into a depression created by the 3-D structure of the antibody. Hydrogen bonds are indicated by yellow lines.	Close up of hydrogen bond between amino acids from antibody and antigen.