Exogenous uridine diphosphoglucuronic acid breakdown in rat small intestinal mucosa preparations. Effect of other nucleotides.

Breakdown of UDPGA incorporated in a mixture containing rat liver or small intestinal mucosa preparations was investigated in the absence of exogenous sugar acceptor. A rapid UDPGA breakdown was seen with intestinal mucosa preparations in such a way that UDPGA decreased to about 1% or less of the initial value after 15 min of incubation. It was estimated that 60 to 70% of total products derived from UDPGA at the end of the incubation with intestinal tissue was in the form of uridine (90%) and uracil (10%). The addition of UDPG, ATP or UDP-N-acetylglucosamine protected UDPGA against degradation by tissue. The results indicated that care must be taken during the incubation of exogenous UDPGA for glucuronyltransferase assay in the intestinal mucosa due to the predominance in this tissue of enzyme systems involved in UDPGA breakdown.