Linked Life Data

7791131

Source:http://linkedlifedata.com/resource/pubmed/id/7791131

Statements in which the resource exists as a subject.
PredicateObject
rdf:type
lifeskim:mentions
pubmed:issue
3
pubmed:dateCreated
1995-7-21
pubmed:abstractText
The photoaffinity analogs [beta-32P]5-azido-UDP-glucuronic acid ([32P]5N3UDP-GlcUA) and [beta-32P]5-azido-UDP-glucose ([32P]5N3UDP-Glc) were used to characterize UDP-glycosyltransferases of microsomes prepared from human liver. Photoincorporation of both probes into proteins in the 50- to 56-kdalton range, known to contain UDP-glucuronosyl transferases (UGTs), was concentration dependent, and photolabeled proteins were susceptible to trypsin digestion only in the presence of detergent. The latter was demonstrated by the appearance on Western blots of the trypsin-treated, detergent-disrupted microsomes of a protein band of slightly lower molecular mass than, and presumably derived from, the UGTs. However, a labeled cleavage product was found only in samples photolabeled with [32P]5N3UDP-GlcUA and not in those labeled with [32P]5N3UDP-Glc. In detergent-treated microsomes, all of the nucleotide sugars that were tested protected better against photoinsertion of [32P]5N3UDP-GlcUA than of [32P]5N3UDP-Glc, with UDP-glucose being the most effective, followed by UDP-GlcUA and UDP-galactose. The pattern of inhibition of a series of uridinyl analogs toward photolabeling by the two probes was quite different: one inhibitor that was ineffective in blocking photoincorporation of [32P]5N3UDP-GlcUA (L-DPASiU) was one of the most potent inhibitors of photolabeling with [32P]5N3UDP-Glc. A similar dichotomy was seen with several inhibitors in enzymatic assays measuring hyodeoxycholic acid 6-O glucuronidation and glucosidation activities; the most potent inhibitors of HDCA glucosidation were not as effective against glucuronidation. The results indicate a lumenal orientation for human microsomal UGTs and provide substantial evidence that two distinct enzyme systems are involved in 6-O glucuronidation and 6-O glucosidation of HDCA.
pubmed:grant
pubmed:language
eng
pubmed:journal
pubmed:citationSubset
IM
pubmed:chemical
pubmed:status
MEDLINE
pubmed:month
Jun
pubmed:issn
0022-3565
pubmed:author
pubmed:issnType
Print
pubmed:volume
273
pubmed:owner
NLM
pubmed:authorsComplete
Y
pubmed:pagination
1551-9
pubmed:dateRevised
2007-11-14
pubmed:meshHeading
pubmed:year
1995
pubmed:articleTitle
Characterization of human liver microsomal UDP-glycosyltransferases using photoaffinity analogs.
pubmed:affiliation
Department of Internal Medicine, University of Arkansas for Medical Sciences, Little Rock, USA.
pubmed:publicationType
Journal Article, Research Support, U.S. Gov't, P.H.S., Research Support, U.S. Gov't, Non-P.H.S.