Interaction of Mitochondrial Aspartate Aminotransferase with Negatively Charged Lecithin Liposomes1

Publisher Website
Google Scholar
Abstract
Several kinds of hydrophilic proteins were examined to determine their interaction with artificial liposomes. [Saccharomyces cerevisiae] mitochondrial aspartate aminotransferase (m-GOT) [EC 2.6.1.1], and cytochrome c interacted strongly with negatively charged liposomes. In each case an appreciable amount of the protein bound to liposomes remained unreleased after raising the salt concentration in the medium. The m-GOT tightly bound to the liposomes became latent in its enzymatic activity and was reversibly activated by solubilization of the liposomes with detergent. This was also the case for cytochrome c, which ceased to be reducible by external reductant, such as dithionite. The tightly bound m-GOT was not susceptible to the proteolytic action of trypsin, or that of Nagarse. These basic proteins apparently interact with acidic liposomes not only electrostatically but also hydrophobically. This kind of hydrophobic interaction was not observed in the combination of positively charged liposomes and acidic proteins, including s-GOT. Mitochondrial GOT was bound to isolated intact mitochondria, but the bound enzyme was fully active, in contrast to the case of acidic liposomes. The hydrophobic interaction of water-soluble protein with liposomes is discussed in connection with the penetration of matrix enzyme through mitochondrial membranes.

This publication has 1 reference indexed in Scilit: