1. Specific gamma-glutamyl transpeptidase inhibitor from human and animal intestines
A Szewczuk, K A Sobiech, M Wellman-Bednawska Arch Immunol Ther Exp (Warsz). 1976;24(3):439-50.
An inhibitor of gamma-glutamyl transpeptidase in human and animal intestines was assayed by means of a new method. In mice fed with LSM fodder, accumulation of the inhibitor in the mucous membrane of the small intestine was observed. Purified gamma-glutamyl transpeptidase inhibitor from mouse and human intestines was identified as L-serine. Neither this amino acid nor purifed inhibitor acted on other intestinal peptidases. Presumably, one of the ingredients of LSM feed influences accumulation of the inhibitor, and consequently diminishes absorption of gamma-glutamyl substrates in the intestine.
2. Arrest of rat embryonic development by the inhibition of gamma-glutamyl transpeptidase. I. Intrauterine administration of L-serine-borate complex
M Díaz-Flores, G Duran-Reyes, J J Hicks Int J Fertil Menopausal Stud. 1994 Jul-Aug;39(4):234-8.
Objective: The purpose of this study was to investigate the activity of gamma-glutamyl transpeptidase (gamma-GTP, E.C. 2.3.2.2) in rat endometrium (day 5 of pregnancy). Since gamma-GTP is an enzyme involved in the translocation of amino acids from fluids toward tissues, these substrates are necessary for anabolic processes. Methods and results: The presence of statistically higher activity of gamma-GTP in rat (Sprague-Dawley) implantation sites (1.06 nmol/mg protein/min) than in nondecidualized (0.87 nmol/mg protein/min) tissues was demonstrated. The intrauterine administration of L-serine-borate complex (5 mM) during day 5 of pregnancy arrested 91.6% of rat embryonic development (day 18). This inhibitory effect was not present when borate or L-serine was administered separately. The L-serine-borate complex also inhibited (by 88%) the gamma-GTP in vitro. Conclusion: The inhibition of gamma-GTP by L-serine-borate complex might be considered as a new approach to the arrest of biological processes in differentiation or development.
3. Variation of human intestinal gamma-glutamyl transpeptidase in ontogenetic development
K A Sobiech, A Szewczuk Arch Immunol Ther Exp (Warsz). 1977;25(4):579-88.
Activity of gamma-glutamyl transpeptidase in human intestines was measured against alpha-naphthylamide and 12 gamma-glutamyl amino acids and peptides as substrate. Distinctly altered activity was found to accompany ontogenetic development. The ratio of the transpeptidase activity tested against monoglutamyl substrates in the intestines of 7-month fetuses, newborns and adults was 15:1:4, whereas the ratio of gamma-glutamyl cyclotransferase activities in the same age groups was 1-0:1-2:1-6. Distinct differences were found in resistance to heating, sensitivity to L-serine plus borate, and other effectors, and electrophoretic mobility, between fetal gamma-glutamyl transpeptidase and the enzyme from adults, which supports the hypothesis of existence of two forms of the enzyme in the human intestines. The results suggest involvement of gamma-glutamyl transpeptidase in the pathomechanism of celiakia in children.
