Abstract
Previous studies have shown the activation of morphine glucuronidation in hepatic microsomes by bilirubin. This report shows that morphine glucuronide synthesis through microsomal UDP-glucuronyltransferase (EC 2.4.1.17) proceeds via a sequential ordered mechanism in the absence and presence of bilirubin and Triton X-100. Bilirubin markedly increases the Vmax, slightly increases the Ka for morphine, and has no effect on the Ka for UDP-glucuronic acid. The activation occurs in intact microsomes but not with a solubilized enzyme preparation. These results may have significance with respect to the stimulation of morphine glucuronidation in vivo.
ACKNOWLEDGMENTS The authors gratefully acknowledge the helpful advice of Dr. Bryce Plapp and the technical assistance of Mrs. Marlene Mecall.
- Copyright ©, 1975, by Academic Press, Inc.
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