Question

How does PDI interact with substrates? What is its final state

A) Covalent binding; reduced state
B) Non-covalent association; oxidized state
C) Enzymatic cleavage; activated state
D) Phosphorylation; phosphorylated state

Answer 1

PDI non-covalently associates with substrates to catalyze the formation and reshuffling of disulfide bonds in proteins, releasing in an oxidized state, reflected by option B) Non-covalent association; oxidized state.

Step-by-step explanation:

PDI, or protein disulfide isomerase, interacts with substrates by forming non-covalent associations and catalyzes the formation and reshuffling of disulfide bonds in proteins. PDI's activity helps proteins to fold properly. It operates by first binding to a substrate through a non-covalent association, then rearranges or forms new disulfide bonds within the substrate protein. Eventually, PDI is released in its oxidized state, where it can go on to catalyze other folding events.

The correct answer to the question of how PDI interacts with substrates and its final state is B) Non-covalent association; oxidized state. During the reaction, PDI helps in the correct folding of proteins by making and breaking disulfide bonds through a non-covalent association with substrates, rather than through covalent binding, enzymatic cleavage, or phosphorylation.