Statements in which the resource exists as a subject.
PredicateObject
rdf:type
lifeskim:mentions
pubmed:issue
2
pubmed:dateCreated
1994-2-18
pubmed:abstractText
Apo-dihydrofolate reductase from Escherichia coli samples two distinct environments slowly on the NMR time scale at room temperature. Several assigned resonances belong to residues in, or proximal to, a loop (loop I) which is comprised of residues 9-24. This exchange process was altered (either removed or made fast on the NMR time scale) by deleting three hairpin turn forming residues from the loop and filling the gap with a single glycine [Li, L., Falzone, C. J., Wright, P. E., & Benkovic, S. J. (1992) Biochemistry 31, 7826-7833]. An approximate value of 35 s-1 for the exchange rate associated with loop I in apo-DHFR was obtained in two-dimensional nuclear Overhauser spectra by analyzing the time dependence of the cross-peak volume for N epsilon H of Trp-22, a residue which is located in this loop and which has resolved cross-peaks. Owing to the critical role that this loop plays in catalysis, the correspondence between this rate of conformational exchange and off-rates for tetrahydrofolate and the reduced nicotinamide cofactor from product and substrate complexes suggests that loop movement may be a limiting factor in substrate turnover.
pubmed:grant
pubmed:language
eng
pubmed:journal
pubmed:citationSubset
IM
pubmed:chemical
pubmed:status
MEDLINE
pubmed:month
Jan
pubmed:issn
0006-2960
pubmed:author
pubmed:issnType
Print
pubmed:day
18
pubmed:volume
33
pubmed:owner
NLM
pubmed:authorsComplete
Y
pubmed:pagination
439-42
pubmed:dateRevised
2007-11-14
pubmed:meshHeading
pubmed:year
1994
pubmed:articleTitle
Dynamics of a flexible loop in dihydrofolate reductase from Escherichia coli and its implication for catalysis.
pubmed:affiliation
Department of Chemistry, Pennsylvania State University, University Park 16802.
pubmed:publicationType
Journal Article, Research Support, U.S. Gov't, P.H.S., Research Support, Non-U.S. Gov't