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Updated: Aug 18, 2026

Unraveling Entropic Rate Acceleration Induced by Solvent Dynamics in Membrane Enzymes
Published on: January 16, 2016
Catalytic facilitation by diffusion of adsorbed substrate on membrane surface
Abstract:
Membrane-alkaline phosphatase shows greater velocity of reaction than solubilized enzyme at low substrate concentration, whereas at saturation-concentration the opposite is true. The catalytic rate enhancement with the membrane-enzyme, when substrate availability is limiting, is attributed to non-specific adsorption of substrate to the membrane followed by its surface-diffusion to the active site resulting in an enhanced collision rate for the substrate with the enzyme. Experimental evidence for the adsorption-diffusion is provided by the dynamic quenching of 1-anilino-naphthalene-8-sulphonate, a membrane-bound probe's fluorescence by the substrate, 4-nitrophenyl-phosphate.
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