[Proteases from the enterocytes of the porcine small intestine. Role of aminopeptidase N in the transport of dipeptides].

The kinetics of radioactive label uptake from [U-14C]Gly, L-[4.5-3H]Leu and dipeptide [U-14C]Gly-L-[4.5-3H]Leu by the brush border membrane vesicles of porcine small intestine have been studied. The effect of aminopeptidase N inhibitors and of leucine-binding protein on the accumulation rates has been investigated. A comparison of the kinetic parameters for the uptake and hydrolysis of Gly-L-Leu, has demonstrated that the dipeptide transfer includes two conjugated steps, i. e., hydrolysis catalyzed by aminopeptidase N and transport of the resultant free amino acids by a specific carrier.