Localization of a narrow‐specificity thyroliberin hydrolyzing pyroglutamate aminopeptidase in synaptosomal membranes of guinea‐pig brain

Abstract

The presence of a particulate pyroglutamate aminopeptidase is reported in guinea pig brain tissue. This activity appears to reside in the synaptosomal membrane and could be released from the membrane by treatment with papain or Triton X-100. By contrast with a previously described broad-specificity soluble pyroglutamate aminopeptidase from guinea pig brain tissue, the enzyme released from the synaptosomal membrane preparation removed pyroglutamic acid from thyroliberin, acid thyroliberin and < Glu-His-Gly alone of the peptides tested. Unlike the soluble tissue enzyme the present enzyme was inhibited by the presence of EDTA and the activity released from synaptosomal membranes by papain had a relative molecular mass of 230,000, almost 1 order of magnitude greater than that reported for the soluble enzyme.