PROLIDASE ACTIVITY IN BRAIN: COMPARISON WITH OTHER ORGANS

Publisher Website
Google Scholar
Abstract
—: Prolidase (imidodipeptidase, EC 3.4.3.7) activity in brain was assayed spectrophotometrically, and the validity of the assay was confirmed by microchromatographic analysis of the dansyl derivatives of the reaction products. The ratio of the activity of prolidase from brain on Ala‐Pro, Gly‐Pro, and Pro‐Pro was similar to that of the highly purified intestinal mucosal prolidase. The size and polarity of the amino acid side chain (R) of the N‐terminal amino acid and whether the terminal amino and carboxy groups are free or blocked are important factors in determining prolidase substrate activity. Using Ala‐Pro as substrate, we found prolidase activity in all rat tissues we investigated, with highest activity in kidney and lowest in plasma; 33 mmol of Ala‐Pro was hydrolyzed per mg of protein per min by brain tissue, which is 20% of the activity for kidney and 23% of that for intestinal mucosa. The specific activity of prolidase was higher in the sciatic nerve than in brain or spinal cord, and activity was higher in the distal portion.