Characterization of active dipeptide transport by germinating barley embryos: Effects of pH and metabolic inhibitors.

A sensitive new fluorescent method is outlined for the study of peptide and amino acid transport processes. Studies on dipeptide transport in germinating barley (Hordeum vulgare.) embryos have provided evidence for accumulation of substrate against a concentration gradient, saturation kinetics, a pH optimum at pH 3.8, and inhibition by a variety of metabolic inhibitors. Acetate also inhibits transport, possibly by disrupting H(+) gradients across the plasma membrane.