RECOGNITION OF AMINO-ACIDS BY MEMBRANE-POTENTIAL OF IMMOBILIZED GLOBULIN MEMBRANES

The shifts in membrane potential, caused by the injection of some amin o acids into a permeation cell, were measured using immobilized gamma- globulin membranes. The shifts in membrane potential were observed to be positive or negative when the isoelectric point of each amino acid injected into the cell was less or higher than 6.0. The potential resp onse caused by the injection of each amino acid shows an individual an d characteristic curve depending on the amino acid, and the difference in potential curves between D-aspartic acid and L-aspartic acid is si gnificantly observed in the immobilized gamma-globulin membranes. The t3/4 value was found to increase in the following order: lysine = glut amic acid < arginine < D-aspartic acid = asparagine < L-aspartic acid < histidine < alanine, where t3/4 indicates the time at which 75% of t he shifts in membrane potential has been observed. The modified membra ne potential theory provides satisfactory explanations for the membran e potential obtained experimentally before and after the injection of L-alanine, and the theoretical shifts can explain the experimental shi fts in membrane potential due to the injection of L-alanine into the c ell. (C) 1995 John Wiley & Sons, Inc.