Linked Life Data

8334117

Source:http://linkedlifedata.com/resource/pubmed/id/8334117

Statements in which the resource exists as a subject.
PredicateObject
rdf:type
lifeskim:mentions
pubmed:issue
27
pubmed:dateCreated
1993-8-20
pubmed:abstractText
13C NMR studies provide a convenient way of obtaining detailed information about tautomeric and ionization states in protein-ligand complexes provided that suitably 13C-labeled molecules are available. In the present study, [4,6,8a-13C]- and [2,4a,7,9-13C]folic acid were synthesized and the 13C NMR spectra of their complexes with Lactobacillus casei dihydrofolate reductase (DHFR) were assigned and analyzed as a function of pH. From these data it was possible to determine the tautomeric and ionization states of the bound folate and to obtain further evidence about the orientation of the pteridine ring in the complexes. In the 13C spectra of the ternary complexes of the 13C-labeled folic acids with DHFR and NADP+, each labeled carbon gave rise to multiple signals, confirming our previous findings that there are three interconverting conformational forms of bound folate (forms I, IIa, and IIb) in the ternary complex (Birdsall et al., 1989b). The 13C spectra of the binary complexes of folate and DHFR also provide direct evidence for the presence of forms IIa and IIb and indirect evidence of some form I at low pH values ( < 5.0). 2D 1H-13C HMQC-NOESY experiments on ternary complexes formed using the [2,4a,7,9-13C]folic acid were used to obtain intermolecular NOEs between the folate H7 proton and protons on the protein, and these provided further characterization of the orientations of the pteridine ring in the different bound forms of folate (form IIb with its pteridine ring in the catalytically active conformation and forms I and IIa with their pteridine rings turned over by 180 degrees).(ABSTRACT TRUNCATED AT 250 WORDS)
pubmed:language
eng
pubmed:journal
pubmed:citationSubset
IM
pubmed:chemical
pubmed:status
MEDLINE
pubmed:month
Jul
pubmed:issn
0006-2960
pubmed:author
pubmed:issnType
Print
pubmed:day
13
pubmed:volume
32
pubmed:owner
NLM
pubmed:authorsComplete
Y
pubmed:pagination
6846-54
pubmed:dateRevised
2006-11-15
pubmed:meshHeading
pubmed:year
1993
pubmed:articleTitle
13C NMR determination of the tautomeric and ionization states of folate in its complexes with Lactobacillus casei dihydrofolate reductase.
pubmed:affiliation
Laboratory of Molecular Structure, National Institute for Medical Research, London, England.
pubmed:publicationType
Journal Article, Research Support, Non-U.S. Gov't