Dataset Information

THE INHIBITION OF THE URIDINE DIPHOSPHATE-TRANSGLUCURONYLASE ACTIVITY OF MOUSE-LIVER HOMOGENATES BY THIOL REAGENTS.

ABSTRACT: 1. A study of the catalysis of the formation of the glucuronides of o-aminophenol and p-nitrophenol by the uridine diphosphate transglucuronylase of homogenates of female mouse liver has been made, with reference to the effect of reagents reacting with thiol groups. 2. The synthesis of both glucuronides was completely inhibited by organic mercurials and N-ethylmaleimide. The inhibition was only partial with arsenite and the arsenoxides, iodoacetamide and o-iodosobenzoate. 3. The o-aminophenol system was much more sensitive than that for p-nitrophenol to all the thiol reagents, except N-ethylmaleimide, which was equally active in both systems. 4. At very low concentrations of the organic mercurials, the o-aminophenol system was activated. 5. With o-aminophenyl glucuronide formation, complete protection was given by glutathione and cysteine against the organic mercurials, N-ethylmaleimide and iodoacetamide, and partial protection against the arsenicals. Reversal was complete against the mercurials, and very limited against the arsenicals and iodoacetamide. The effects of N-ethylmaleimide and o-iodosobenzoate were irreversible. Results with p-nitrophenol were very similar. 6. Uridine diphosphate transglucuronylase was partially protected against p-chloromercuribenzoate and lewisite oxide by uridine diphosphate glucuronate, but not by o-aminophenol. 7. Glutathione did not prevent the decline in the rate of conjugation of o-aminophenol when homogenates were aged by incubation at 30 degrees . Cysteine was unable to prevent or reverse inactivation by ultrasonic radiation.

SUBMITTER: STOREY ID

PROVIDER: S-EPMC1215194 | biostudies-other | 1965 Apr

REPOSITORIES: biostudies-other

ACCESS DATA

Similar Datasets

Project description:1. The liver of the domestric fowl (Gallus gallus) remains capable of conjugating o-aminophenol with glucuronic acid after 8 days' culture. The pathway of o-aminophenyl glucuronide formation in cultured liver, as in fresh tissue, includes the enzyme UDP-glucuronyltransferase. 2. UDP-glucuronyltransferase activity in chick-embryo liver increases on culture from very low to adult values within 6-8 days. 3. The development of UDP-glucuronyltransferase activity in cultured chick-embryo liver requires certain serum factors in the medium. The requirements change with embryo age. Liver from embryos younger than 15 days develops enzyme activity equally well in media containing either foetal or adult serum; liver from embryos older than 16 days develops activity only with adult serum. The development of enzyme activity in liver from the older embryos appears to be stimulated by diffusible factors in adult serum and inhibited by diffusible factors in foetal serum. It is suggested that the stimulation and inhibition of enzyme formation by small, diffusible molecules may be part of the mechanism regulating UDP-glucuronyltransferase activity in vivo. 4. Liver from 19-day-old chick embryos cultured with foetal serum begins to develop UDP-glucuronyltransferase activity if transferred to an adult-serum medium. Its capacity to develop UDP-glucuronyltransferase activity in adult serum survives in a foetal-serum medium for at least 5 days, the longest period tested. 5. The activity of UDP-glucuronyltransferase reached in 19-day chick-embryo liver after 1 or 2 days with adult serum is maintained without further increase after transfer to a foetal-serum medium. After 3 days with adult serum UDP-glucuronyltransferase activity continues to increase when the tissue is transferred to a foetal-serum medium. Thus liver from 19-day-old embryos requires 3 days with adult serum before development of enzyme activity becomes independent of a continuous adult-serum environment.

Dataset Information

THE INHIBITION OF THE URIDINE DIPHOSPHATE-TRANSGLUCURONYLASE ACTIVITY OF MOUSE-LIVER HOMOGENATES BY THIOL REAGENTS.

Similar Datasets

OmicsDI is part of the ELIXIR infrastructure

Tweets