Linked Life Data

16641

Source:http://linkedlifedata.com/resource/pubmed/id/16641

Statements in which the resource exists as a subject.
PredicateObject
rdf:type
lifeskim:mentions
pubmed:issue
10
pubmed:dateCreated
1977-7-18
pubmed:abstractText
Human carbonic anhydrase B (HCAB), prepared by a new affinity chromatography procedure, was carboxymethylated exclusively at NT of its active-site histidine-200 using 90% [1-13C]bromoacetate. The 13C nuclear magnetic resonance signal of the covalently attached carboxylate was easily detected over the natural abundance background due to the other carbonyl and carboxyl carbons of this 29 000 molecular weight zinc metalloenzyme. Its chemical shift proved very sensitive to the presence of inhibitors in the active site and to variations in pH. Two perturbing groups with pKa values of 6.0 and 9.2 were assigned to the modified histidine-200 itself and the zinc-bound water ligand, respectively, making use of 13C NMR titration data on Nr- and Nr-carboxymethyl-L-histidine model compounds. The results rule out histidine-200 as the critical group whose ionization controls the catalytic activity. They also strongly suggest an interaction of the carboxylate of the carboxymethyl group with either the zinc or its water ligand around pH 8, possibly explaining the basis for the major differences between HCAB and CmHCAB.
pubmed:language
eng
pubmed:journal
pubmed:citationSubset
IM
pubmed:chemical
pubmed:status
MEDLINE
pubmed:month
May
pubmed:issn
0006-2960
pubmed:author
pubmed:issnType
Print
pubmed:day
17
pubmed:volume
16
pubmed:owner
NLM
pubmed:authorsComplete
Y
pubmed:pagination
2241-7
pubmed:dateRevised
2006-11-15
pubmed:meshHeading
pubmed:year
1977
pubmed:articleTitle
Carbon-13 nuclear magnetic resonance probe of active-site ionizations in human carbonic anhydrase B.
pubmed:publicationType
Journal Article, Research Support, U.S. Gov't, P.H.S.