HYDROLYSIS OF N-BENZOYL-L-TYROSYL-PARA-AMINOBENZOIC ACID BY RAT-KIDNEY

The ability of extrapancreatic tissues of the rat to hydrolyze bentiromide (N-benzoyl-l-tyrosyl-p-aminobenzoic acid), a chymotrypsinlabile peptide used as a diagnostic agent for exocrine pancreatic function, was determined. Rat kidney, and to a much lesser degree, rat liver, hydrolyzed the peptide to yield free PABA. The rat kidney enzyme also resembled chymotrypsin with respect to its pH optimum. However, unlike chymotrypsin and the rat liver enzyme, rat kidney was devoid of esterolytic activity. The bentiromide-splitting enzyme was present in both the renal cortex and the medulla, was particle-bound, and was nonlysosomal. Small but detectable amounts of the enzyme were also present in guinea pig kidney but there was no detectable activity in either rabbit or swine kidney. © 1979.