Linked Life Data

6799002

Source:http://linkedlifedata.com/resource/pubmed/id/6799002

Statements in which the resource exists as a subject.
PredicateObject
rdf:type
lifeskim:mentions
pubmed:issue
1
pubmed:dateCreated
1982-4-20
pubmed:abstractText
Dihydrofolate reductase from Lactobacillus casei was inactivated by reaction with tetranitromethane and 7-chloro-4-nitrobenzo-2-oxa-1,3-diazole. Loss of activity occurred with modification of four of the five tyrosine residues present in the enzyme. The presence of either substrate, NADPH or 7,8-dihydrofolate, as well as NADP and folate, provided extensive protection against inactivation, while NADH and tetrahydrofolate exhibited none. This protection from inactivation occurred on protection of two of the four susceptible tyrosines from modification. Nitration of the enzyme adversely affected its ability to bind substrates. Restoration of the pKa of the nitrated tyrosines by reduction of the nitro group to an amino group did not result in a regeneration of enzymatic activity. However, fluorotyrosine-containing enzyme, prepared by growing the bacterium in the presence of fluorotyrosine, exhibited specific activity identical to that of native enzyme over the pH range of 4.5-8. These results suggest that inactivation of dihydrofolate reductase by tyrosine modification occurs primarily due to a steric effect and that the active site tyrosines may participate in substrate binding.
pubmed:grant
pubmed:language
eng
pubmed:journal
pubmed:citationSubset
IM
pubmed:chemical
pubmed:status
MEDLINE
pubmed:month
Feb
pubmed:issn
0006-3002
pubmed:author
pubmed:issnType
Print
pubmed:day
4
pubmed:volume
701
pubmed:owner
NLM
pubmed:authorsComplete
Y
pubmed:pagination
49-56
pubmed:dateRevised
2007-11-14
pubmed:meshHeading
pubmed:year
1982
pubmed:articleTitle
Modification of tyrosine residues in dihydrofolate reductase from Lactobacillus casei.
pubmed:publicationType
Journal Article, Research Support, U.S. Gov't, P.H.S., Research Support, Non-U.S. Gov't