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Superficially Active Water in Lipid Membranes and Its Influence on the Interaction of an Aqueous Soluble Protease

M F Martini, E A Disalvo

Biochim Biophys Acta. 2007 Oct;1768(10):2541-8.

PMID: 17662235

Abstract:

The purpose of this paper is to demonstrate that the interaction of an aqueous soluble enzyme with lipid membranes is influenced by the lipid composition of the interphase. The results show that the interaction of an aqueous soluble protease, Rennet from Mucor miehei, depends on the exposure of the carbonyl and phosphate groups at the membrane interphase. The changes produced by the protease on the surface pressure of monolayers of dimyristoylphosphatidylcholine (DMPC); dioleoylphosphatidylcholine (DOPC); diphytanoylphosphatidylcholine (DPhPC); dipalmitoylphosphatidylcholine (DPPC); di-O-tetradecylphosphatidyl-choline [D(ether)PC]; dimyristoylphosphatidylethanolamine (DMPE); di-O-tetradecyl-phosphatidylethanolamine [D(ether)PE] were measured at different initial surface pressures. The meaning of the DeltaPi vs. Pi curves was interpreted in the light of the concept of interphase given by Defay and Prigogine [R. Defay, I. Prigogine, Surface Tension and Adsorption, John Wiley & Sons, New York, 1966, pp. 273-277] considering the interphase as a bidimensional solution of polar head groups. With this approach, and based on reported evidences that carbonyls and phosphates are the main hydration sites of the lipid membranes, it is suggested that the mechanism of interaction of aqueous soluble protein involves water beyond the hydration shell. At high surface pressure, only water strongly bound to carbonyl and phosphate groups is present and the interaction is not occurring. In contrast, at low surface pressures, the protease-membrane interaction is a function of acyl chain for different polar groups. This is interpreted, as a consequence of the changes in the interfacial tension produced by the displacement of water confined between the hydrated head groups.

Chemicals Related in the Paper:

Catalog Number Product Name Structure CAS Number Price
AP9042084 Rennet from Mucor miehei Rennet from Mucor miehei 9042-08-4 Price
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