Linked Life Data

2007565

Source:http://linkedlifedata.com/resource/pubmed/id/2007565

Statements in which the resource exists as a subject.
PredicateObject
rdf:type
lifeskim:mentions
pubmed:issue
10
pubmed:dateCreated
1991-5-1
pubmed:abstractText
The conversion of dopachrome to dihydroxyindole(s), a key reaction in eumelanin biosynthetic pathway, has been shown to be under the control of dopachrome conversion factor. Dopachrome conversion factor isolated from the hemolymph of Manduca sexta larvae, which is devoid of any tyrosinase activity, exhibits a narrow substrate specificity and readily bleaches the iminochromes derived from the oxidation of L-dopa, L-dopa methyl ester, and alpha-methyl-L-dopa, but failed to attack the corresponding D-isomers. The product formed in the case of L-dopachrome was identified to be 5,6-dihydroxyindole. Therefore, aromatization of dopachrome seems to accompany its decarboxylation as well. However, the enzyme also converts L-dopachrome methyl ester to an indole derivative indicating that it can deprotonate the alpha-hydrogen when the carboxyl group is blocked. These results are accounted for by the transient formation and further transformation of a reactive quinone methide intermediate during the dopachrome conversion factor-catalyzed reaction. The fact that the enzyme-catalyzed conversion of alpha-methyl dopachrome methyl ester (where both decarboxylation and deprotonation are blocked) resulted in the generation of a stable quinone methide in the reaction mixture confirms this contention and supports our recent proposal that quinone methide and not indolenine is the key transient intermediate in the conversion of dopachrome to dihydroxyindole observed during melanogenesis.
pubmed:grant
pubmed:language
eng
pubmed:journal
pubmed:citationSubset
IM
pubmed:chemical
pubmed:status
MEDLINE
pubmed:month
Apr
pubmed:issn
0021-9258
pubmed:author
pubmed:issnType
Print
pubmed:day
5
pubmed:volume
266
pubmed:owner
NLM
pubmed:authorsComplete
Y
pubmed:pagination
6073-8
pubmed:dateRevised
2007-11-14
pubmed:meshHeading
pubmed:year
1991
pubmed:articleTitle
Quinone methide as a new intermediate in eumelanin biosynthesis.
pubmed:affiliation
Department of Biology, University of Massachusetts, Boston 02125.
pubmed:publicationType
Journal Article, Research Support, U.S. Gov't, P.H.S., Research Support, Non-U.S. Gov't