Question

Proteins are dynamic entities that undergo _______

(a) only fluctuation of flexible loop regions about equilibrium positions when in solution

(b) only limited conformational change of amino acid side-chains when in solution

(c) both limited conformational change of amino acid side-chains and fluctuation of flexible loop regions about equilibrium positions when in solution

(d) illimitable or total conformational change of amino acid side-chains when in solution

I have been asked this question during an interview.

This intriguing question originated from Conformational Flexibility in portion Predicting the Structure of Protein – Biomolecular Interactions of Bioinformatics

Answer 1

Correct answer is (c) both limited conformational change of amino acid side-chains and fluctuation of flexible loop regions about equilibrium positions when in solution

Easiest explanation: Such flexibility can often be adequately treated by ‘soft’ potentials or limited conformational flexibility and/or refinement of side-chains on docking. However, proteins often undergo more extensive conformational changes which may involve large-scale motions of domains relative to one another or possibly conformational change involving order-disorder transitions.