Linked Life Data

1420151

Source:http://linkedlifedata.com/resource/pubmed/id/1420151

Statements in which the resource exists as a subject.
PredicateObject
rdf:type
lifeskim:mentions
pubmed:issue
42
pubmed:dateCreated
1992-11-27
pubmed:abstractText
The proposed roles of Cys148 and Asp179 in deoxycytidylate (dCMP) hydroxymethylase (CH) have been tested using site-directed mutagenesis. CH catalyzes the formation of 5-(hydroxymethyl)-dCMP, essential for DNA synthesis in phage T4, from dCMP and methylenetetrahydrofolate. CH resembles thymidylate synthase (TS), an enzyme of known three-dimensional structure, in both amino acid sequence and the reaction catalyzed. Conversion of Cys148 to Asp, Gly, or Ser decreases CH activity at least 10(5)-fold, consistent with a nucleophilic role for Cys148 (analogous to the catalytic Cys residue in TS). In crystalline TS, hydrogen bonds connect O4 and N3 of the substrate dUMP to the side-chain amide of an Asn; the corresponding residue in CH is Asp179. Conversion of Asp179 to Asn reduces the value of kcat/KM for dCMP by (1.5 x 10(4))-fold and increases the value of kcat/KM for dUMP by 60-fold; as a result, CH(D179N) has a slight preference for dUMP. Wild-type CH and CH(D179N) are covalently inactivated by 5-fluoro-dUMP, a mechanism-based inactivator of TS. Asp179 is proposed to stabilize covalent catalytic intermediates, by protonating N3 of the pyrimidine-CH adduct.
pubmed:grant
pubmed:language
eng
pubmed:journal
pubmed:citationSubset
IM
pubmed:chemical
pubmed:status
MEDLINE
pubmed:month
Oct
pubmed:issn
0006-2960
pubmed:author
pubmed:issnType
Print
pubmed:day
27
pubmed:volume
31
pubmed:owner
NLM
pubmed:authorsComplete
Y
pubmed:pagination
10315-21
pubmed:dateRevised
2007-11-14
pubmed:meshHeading
pubmed:year
1992
pubmed:articleTitle
Roles of Cys148 and Asp179 in catalysis by deoxycytidylate hydroxymethylase from bacteriophage T4 examined by site-directed mutagenesis.
pubmed:affiliation
Department of Pharmacology, University of Massachusetts Medical Center, North Worcester 01655.
pubmed:publicationType
Journal Article, Research Support, U.S. Gov't, P.H.S.