A novel inhibitor of beta-glucuronidase: L-aspartic acid

Infants who consume casein hydrolysate formula have been shown to have lowe r neonatal jaundice levels than infants who consume. routine formula or bre ast milk. Because casein hydrolysate has been shown to contain a beta -glac uronidase inhibitor, one possible mechanism to explain this finding is bloc kage of the enterohepatic circulation of bilirubin by a component of the fo rmula. The aim of this research was to identify the source of the beta -glu curonidase inhibition in hydrolyzed casein. A beta -glucuronidase inhibitio n assay and measurements of physical and kinetic parameters were used to an alyze the. components of hydrolyzed casein and infant formulas. Kinetic stu dies used purified beta -glucuronidase. The L-aspartic acid in. hydrolyzed casein accounts for the majority of the beta -glucuronidase inhibition pres ent. Kinetic studies indicate a competitive inhibition mechanism. L-Asparti c acid is a newly identified competitive inhibitor of beta -glucuronidase.