Linked Life Data

3079764

Source:http://linkedlifedata.com/resource/pubmed/id/3079764

Statements in which the resource exists as a subject.
PredicateObject
rdf:type
lifeskim:mentions
pubmed:issue
2
pubmed:dateCreated
1986-2-14
pubmed:abstractText
Two forms of cytochrome P-450 (P-450), designated P-450MP-1 and P-450MP-2, were purified to electrophoretic homogeneity from human liver microsomes on the basis of mephenytoin 4-hydroxylase activity. Purified P-450MP-1 and P-450MP-2 contained 12-17 nmol of P-450/mg of protein and had apparent monomeric molecular weights of 48,000 and 50,000, respectively. P-450MP-1 and P-450MP-2 were found to be very similar proteins as judged by chromatographic behavior on n-octylamino-Sepharose 4B, hydroxylapatite, and DEAE- and CM-cellulose columns, spectral properties, amino acid composition, peptide mapping, double immunodiffusion analysis, immunoinhibition, and N-terminal amino acid sequences. In vitro translation of liver RNA yielded polypeptides migrating with P-450MP-1 or P-450MP-2, depending upon which form was in each sample, indicating that the two P-450s are translated from different mRNAs. When reconsituted with NADPH-cytochrome-P-450 reductase and L-alpha-dilauroyl-sn-glyceryo-3-phosphocholine, P-450MP-1 and P-450MP-2 gave apparently higher turnover numbers for mephenytoin 4-hydroxylation than did the P-450 in the microsomes. The addition of purified rat or human cytochrome b5 to the reconstituted system caused a significant increase in the hydroxylation activity; the maximum stimulation was obtained when the molar ratio of cytochrome b5 to P-450 was 3-fold. Rabbit anti-human cytochrome b5 inhibited NADH-cytochrome-c reductase and S-mephenytoin 4-hydroxylase activities in human liver microsomes. In the presence of cytochrome b5, the Km value for S-mephenytoin was 1.25 mM with all five purified cytochrome P-450s preparations, and Vmax values were 0.8-1.25 nmol of 4-hydroxy product formed per min/nmol of P-450. P-450MP is a relatively selective P-450 form that metabolizes substituted hydantoins well. Reactions catalyzed by purified P-450MP-1 and P-450MP-2 preparations and inhibited by anti-P-450MP in human liver microsomes include S-mephenytoin 4-hydroxylation, S-nirvanol 4-hydroxylation, S-mephenytoin N-demethylation, and diphenylhydantoin 4-hydroxylation. Thus, at least two very similar forms of human P-450 are involved in S-mephenytoin 4-hydroxylation, an activity which shows genetic polymorphism.
pubmed:grant
pubmed:language
eng
pubmed:journal
pubmed:citationSubset
IM
pubmed:chemical
pubmed:status
MEDLINE
pubmed:month
Jan
pubmed:issn
0021-9258
pubmed:author
pubmed:issnType
Print
pubmed:day
15
pubmed:volume
261
pubmed:owner
NLM
pubmed:authorsComplete
Y
pubmed:pagination
909-21
pubmed:dateRevised
2007-11-14
pubmed:meshHeading
pubmed-meshheading:3079764-Amino Acid Sequence, pubmed-meshheading:3079764-Amino Acids, pubmed-meshheading:3079764-Animals, pubmed-meshheading:3079764-Antibodies, pubmed-meshheading:3079764-Aryl Hydrocarbon Hydroxylases, pubmed-meshheading:3079764-Cytochrome P-450 Enzyme System, pubmed-meshheading:3079764-Cytochrome b Group, pubmed-meshheading:3079764-Cytochromes b5, pubmed-meshheading:3079764-Electrophoresis, Polyacrylamide Gel, pubmed-meshheading:3079764-Humans, pubmed-meshheading:3079764-Immunodiffusion, pubmed-meshheading:3079764-Immunosorbent Techniques, pubmed-meshheading:3079764-Kinetics, pubmed-meshheading:3079764-Microsomes, Liver, pubmed-meshheading:3079764-Mixed Function Oxygenases, pubmed-meshheading:3079764-Molecular Weight, pubmed-meshheading:3079764-NADP, pubmed-meshheading:3079764-Polymorphism, Genetic, pubmed-meshheading:3079764-Protein Biosynthesis, pubmed-meshheading:3079764-Rabbits, pubmed-meshheading:3079764-Rats, pubmed-meshheading:3079764-Stereoisomerism
pubmed:year
1986
pubmed:articleTitle
Human liver microsomal cytochrome P-450 mephenytoin 4-hydroxylase, a prototype of genetic polymorphism in oxidative drug metabolism. Purification and characterization of two similar forms involved in the reaction.
pubmed:publicationType
Journal Article, Research Support, U.S. Gov't, P.H.S., Research Support, Non-U.S. Gov't