The catalytic efficiency of two different enzymes can be compared by the -

88 2005 AIPMT BiomoleculesEnzyme Kinetics Medium
The catalytic efficiency of two different enzymes can be compared by the -
A The Km value
B The pH optimum value
C Molecular size of the enzyme
D Formation of the product

Detailed Solution

The Michaelis constant ($K_m$) is the substrate concentration at which the rate of an enzyme-catalysed reaction is half of its maximum velocity ($V_{max}/2$).
$K_m$ is a measure of the affinity of the enzyme for its substrate.
A low $K_m$ means that the enzyme reaches half its maximum rate at a low substrate concentration, i.e. it has a high affinity for the substrate and is more efficient.
A high $K_m$ means a low affinity.
So the catalytic efficiencies of two different enzymes can be compared by their $K_m$ values.
The pH optimum, the molecular size and the mere formation of product do not give such a comparison.

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