Human serum pyroglutamyl-beta-naphthylamide hydrolyzing activity during development and aging

Pypoglutamyl-beta-naphthylamide hydrolyzing activity (pGluHA) is reported t o be capable of removing the amino-terminal pyroglutamic acid residue from peptides (e.g. TRH or GnRH) and artificial substrates. However, its functio nal role in serum is not yet understood. The aim of the present study was t o analyze the activity of pGluHA in human serum during development and agin g, in an apparently healthy population of 139 men and 148 women. To measure pGluHA we used pGlu-beta-naphthylamide as the substrate. Sex differences a nd age-related changes were observed in men and women. In addition, the dev elopmental profile was notably different between men and women. In men, act ivity increased steadily until full sexual maturity, but did not change sub stantially after puberty. In women, activity increased significantly in adv anced ages but there were no significant changes in the rest of the age gro ups tested. Significant sex differences were observed in subjects 46-65 yea rs old, the activity being higher in men than women. In the total populatio n, a significant direct correlation was observed between pGluHA and age. Co nsidered independently, men and women also showed a highly significant dire ct correlation between pGluHA and age. These results may reflect changes in the functional status of its circulating substrates during development and aging. (C) 1999 Elsevier Science Ireland Ltd. All rights reserved.