Interaction of amino acids with glycyl-glycine transport in the mammalian intestine
V Ganapathy M D Hellier A N Radhakrishnan
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In order to investigate a possible interaction between free amino acids and dipeptides during their mucosal uptake in man and monkey, perfusion studiesin vivo and uptake studiesin vitro using labelled and non-labelled dipeptides and amino acids have been carried out. In contrast to the observations of other workers, inhibition of glycyl-glycine uptake was observed with free leucine and methioninc but not with glycine, proline, hydroxyproline or alanine. Leucine and methionine caused inhibition of cytosol glycyl-glycine hydrolase activity, while glycine had no effect. The dipeptide uptake and dipeptide hydrolysis by cytosol enzyme was competitively inhibited by leucine. Although brush border glycyl-glycine hydrolase was also inhibited by leucine, the inhibition was noncompetitive. These data indicate that a few free amino acids can interact with dipeptides during uptake. This interaction might occur either at the transport step or at the stage of intracellular dipeptide hydrolysis.
V Ganapathy1 M D Hellier1 A N Radhakrishnan1
Volume 48, 2023
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