Exchange diffusion of D-leucine in mouse Ehrlich ascites tumor cells.

The present investigation was undertaken to examine an evidence for the exchange diffusion of D-leucine as well as L-leucine and further to study the effect of temperature reduction on the exchange diffusion, in Ehrlich ascites tumor cells in vitro. The homoexchange diffusion for D-leucine was observed at 37 degrees C, the extent being nearly equal to that for L-leucine. The heteroexchange diffusion between D- and L-leucines also occurred at 37 degrees C. These findings were compatible with an assumption that there is a common pathway for D- and L-leucine transport in the tumor cells. It was demonstrated that the exchangeability of D-leucine was depressed remarkably at 0 degree C, while L-leucine still had a considerable exchangeability. This difference in exchangeability of D- and L-leucines in temperature reduction seems to reflect that the bulky hydrocarbon side chains of both the isomers are bound to the different site of carrier as described in the preceding paper.