gamma-Glutamyl transpeptidase activity along the small intestine of sheep: potential areas of amino acid and peptide transport.

Total homogenates of small intestinal sections (10 cm) from 16 wethers and ewes were used to investigate the distribution of gamma-glutamyl transpeptidase activity along the small intestine. gamma-Glutamyl transpeptidase activity was assayed per gram wet tissue, per milligram protein, and total units of enzyme activity per section. Additionally, glutathione was measured. The small intestine had areas of relatively high and low gamma-glutamyl transpeptidase activity, regardless of activity expression (high/low ratio = 5) and corresponding glutathione. Variation of enzyme activity was related to intestinal mucosa, with higher activity resulting from more enzyme activity per milligram of mucosal microvillus-membrane. The comparison of all high gamma-glutamyl transpeptidase activity from all animals showed small intestine of sheep had a region with high activity closest to the pylorus and other high activity locations between 3.75 m and 12.5 m (upper- to mid-jejunum) and between 21 m and 25 m (terminal ileum) from the pylorus. The latter two areas of high activity correspond to areas previously identified as being active in amino acid absorption.