Lipid-dependent interaction of D-beta-hydroxybutyrate dehydrogenase with cellular membranes.

A mechanism of selective localization of membrane-bound enzymes was examined by studying the interaction between D-beta-hydroxybutyrate dehydrogenase (EC 1.1.1.30) and native cellular membranes in which the lipid components were altered. (1) The catalytic activity of the purified lipid-free enzyme could be restored by the re-interaction with microsomal and mitochondrial membranes, whereas with erythrocyte membranes or liposomes from lipids of erythrocyte membranes this activity could not be restored (Miyahara, M., Utsumi, K. and Deamer, D.W. (1981) Biochim. Biophys. Acta 641, 222-231). In the erythrocyte lipid components, only lysophosphatidylcholine markedly inhibited the enzyme reactivation. (2) The inhibitory effect of lysophosphatidylcholine was confirmed in microsomes in which the lysophosphatidylcholine contents had been increased, by phospholipase A2 treatment, to the levels in erythrocyte membranes. (3) Selective digestion by phospholipase C of phosphatidylcholine in the microsomes was accompanied by a lowering of the level of reactivation in the membranes. (4) The presence of lipophilic alkyl compounds such as cetylamine and cetyltrimethylammonium bromide, which contain the ammonium group, in the membranes also inhibited the enzyme reactivation. However, negatively charged and neutral alkyl compounds were less suppressive. The results above suggested that the interaction of D-beta-hydroxybutyrate dehydrogenase with native cellular membranes is dependent on the amounts of phosphatidylcholine and lysophosphatidylcholine exposed on the membrane surface. It was also suggested that the presence of the ammonium group of non-diacyl compounds is unfavorable for the effective interaction of the enzyme.