| Abstract: | The lipids of Micrococcus lysodeikticus membranes were 50%-substituted by phosphatidyl choline using lipid-exchanging proteins isolated from rat liver. The incorporation of phosphatidyl choline into the membrane did not significantly change the malate dehydrogenase activity and the temperature dependence activity in the Arrhenius plots for the enzyme. Gramicidin S--modifier of membrane lipids--had similar effects both on the intact membranes and on the phosphatidyl-enriched membranes. A conclusion is made on structural heterogeneity of the bacterial membrane and on the presence of a boundary lipid fraction, which controls the functioning of malate dehydrogenase and is characterized by a low-rate exchange with other lipids. |
