Enzymes · NEET PG Preparation Biochemistry
Allosteric enzymes characteristically show sigmoidal kinetics rather than hyperbolic kinetics on a velocity versus substrate concentration plot. This…
Practice question from Enzymes (NEET PG Preparation Biochemistry), with the correct answer and a step-by-step solution.
hard · MCQ · Q-90150D
Allosteric enzymes characteristically show sigmoidal kinetics rather than hyperbolic kinetics on a velocity versus substrate concentration plot. This behavior is primarily a result of which of the following phenomena?
- A.Irreversible covalent modification of the catalytic subunit
- B.Cooperative binding of substrate molecules among multiple subunitsCorrect answer
- C.Competitive inhibition by downstream metabolic end-products
- D.Total absence of a quaternary protein structure
Solution
Allosteric enzymes typically possess multiple subunits and active sites. The binding of a substrate molecule to one active site induces a conformational change that alters the affinity of neighboring active sites, a phenomenon known as cooperativity. This gives rise to the characteristic sigmoidal (S-shaped) saturation curve.
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