Control of maize lipid transfer protein activity by oxido-reducing conditions

The activity of lipid transfer proteins (LTPs) isolated from maize, able to facilitate phospholipid movement between membranes, was studied under various oxido-reducing conditions. A progressive inactivation of LTP transfer activity was observed with increasing concentrations of reduced dithiothreitol (DTTred). This inactivation was accompanied by an increase in SH titer as well as by changes of the protein conformation deduced from its higher mobility in SDS-PAGE. By contrast, DTTred did not affect the formation of lipid-LTP complex. Transfer activity and original electrophoretic mobility were partially restored under reoxidation by air or oxidized DTT. Together, these results demonstrate the critical role of correct S-S bondings on LTP activity and suggest a possible in vivo regulation, according to the specific oxido-reducing conditions prevailing in different cell compartments.