Question

Describe the role of metabolic channeling and compartmentation in regulation of
metabolism.

Answer 1

Role of metabolic channeling and compartmentation in regulation of metabolism.

Channeling-

1-Metabolic channeling is the term used to describe the restricted flow of substrates and products in multienzyme systems.(pyruvate dehydrogenase, fatty acid synthetase, glutamine synthetase, proteasome, Rubisco etc).

2-Substrate channeling is a process by which two or more sequential enzymes in a pathway interact to transfer a metabolite (or intermediate) from one enzyme active site to another without allowing free diffusion of the metabolite into the bulk solution.

3-Channeling can make a metabolic pathway more rapid and efficient than it would be if the enzymes were randomly distributed in the cytosol(aqueous component of the cytoplasm of a cell), or prevent the release of unstable intermediates.

4-It can also protect an intermediate from being consumed by competing reactions catalyzed by other enzymes.

NOTE:-Role of enzymes in metabolism help to break down large nutrient molecules, such as proteins, fats, and carbohydrates, into smaller molecules. This process occurs during the digestion of foodstuffs in the stomach and intestines of animals.

Examples of substrate channeling :- purine and pyrimidine biosynthesis, amino acid metabolism, lipid metabolism, glycolysis, the tricarboxylic acid cycle, DNA replication, RNA synthesis, and protein biosynthesis.

Compartmentalization-subcellular structures have specific role in both metabolic pathways and their regulation within cell metabolism.

1-All reactions occurring in cells take place in certain space i.e.. compartment, which is separated from other compartments by means of semipermeable membranes.

2-They help to separate even chemically quite heterogeneous environments and so to optimize(enhance) the course of chemical reactions.

3-Compartmentation is an important component of metabolic regulation. Many metabolic pathways are highly compartmentalized, for example, between different subcellular organelles. In all eukaryotic cells, compartmentation of metabolism within organelles concentrates enzymes and metabolites and also separates them, as a means of controlling reactions.

4-Compartmentalization enhance the property of semi-permeability that help in regulation.