Carbohydrate and sulfate conjugations of p-nitrophenol by hepatopancreas of Homarus americanus

Abstract

1. Glucosyltransferase activity is present in hepatopancreas of Homarus americanus. The enzyme appears to have a specific requirement for UDP-glucose, and ADP-, CDP- or GDP-glucose do not substitute for it. The activity is mainly microsomal, exhibits a pH optimum at 7.9–8.1, and its apparent K m values are 2 mM and 0.3 mM for UDP-glucose and p-nitrophenol respectively. Microsomal glucosyltransferase activity increases with increasing temperature up to 45°. 2. Hepatopancreas possesses a very active sulfotransferase which utilizes 3′-phosphoadenosine-5′-phosphosulfate for sulfoconjugation of p-nitrophenol. The activity is associated chiefly with the soluble fraction and amounts to about 16 nmoles/mg protein/30 min. 3. No detectable glucuronidation of p-nitrophenol occurred when preparations of hepatopancreas fortified with UDP-glucuronic acid were incubated with p-nitrophenol.