Abstract
A biomembrane mainly consists of proteins (enzymes) and phospholipid bilayer. The ratio of both components, and the composition and kind of phospholipids are diverse, though they are almost constant, depending on the kind and site of tissues and the kind of living things. Such relationship of an enzyme with phospholipids is thought important for the action of enzyme. However, the relationship has been little investigated in detail. In this paper, six kinds of phospholipids were synthesized and used as reaction fields for hydrolyses of amino acid esters with a glycolipid as hydrolase model. Phospholipids were found to be classified into three groups : (1) a lipid deactivating the glycolipid by strong hydrogen bond (phosphatidic acid analog), (2) a lipid likely to distribute the glycolipid rather homogeneously by weak hydrogen bond (phosphatidylglycerol and phosphatidylinositol analogs), and (3) a lipid enhancing the activity of a glycolipid by electrostatic effect (phosphatidylserine, phosphatidylcholine, and phosphatidylethanolamine analogs). In addition, especially, phosphatidylserine analog seemed to contribute to the activation of a membrane, resulting in the enhancement of the catalytic activity of glycolipid, even in the presence of phosphatidic acid analog.
