Question

What is the benefit of substrate channeling? The PDH active site forms in the hydrophobic core of the complex instead of a surface‑exposed region. Reaction intermediates move to sequential active sites faster than the diffusion constant. Every intermediate or product made by the PDH complex enters the citric acid cycle as a substrate. The PDH complex sequesters excess substrate to use at later time. Intermediates of a multistep reaction sequence do not dissociate from the enzyme complex.

Answer 1

Intermediates of a multistep reaction sequence do not dissociate from the enzyme complex.

Step-by-step explanation:

Substrate channeling is the process in which intermediates produced in an enzymatic reaction is transferred to another enzyme or active in a reaction pathway without the substrate having to dissociate from the enzymes active sites into the reaction medium or solution.

Benefits of substrate channeling include:

• intermediates of a multistep reaction sequence do not diffuse away from the catalytic sites of enzymes in the pathway thereby ensuring that their concentration remains high

• there is greater control of the flow metabolites in the pathway
• other competing enzymes for a common substrate do not make use of the substrates
• increased efficiency of the catalytic process

Substrate channeling is observed in the pyruvate dehydrogenase complex reaction which oxidizes pyruvate to acetyl-CoA.