Linked Life Data

3707919

Source:http://linkedlifedata.com/resource/pubmed/id/3707919

Statements in which the resource exists as a subject.
PredicateObject
rdf:type
lifeskim:mentions
pubmed:issue
8
pubmed:dateCreated
1986-7-15
pubmed:abstractText
The pyridoxal form of the alpha subform of cytosolic aspartate aminotransferase (EC 2.6.1.1) is fully active and binds pyridoxal 5'-phosphate via an aldimine formation with Lys-258 whereas the gamma subform is virtually inactive and lacks the aldimine linkage. Comparison of 1H NMR spectra between the alpha and gamma subforms suggested that peak 1 of the alpha subform at 8.89 ppm contains a resonance assignable to the internal aldimine 4'-H. Reaction with a reagent that cleaves or modifies the internal aldimine bond [(amino-oxy)acetate, L-cysteinesulfinate, NH2OH, NaBH4, or NaCNBH3] caused the disappearance of a resonance line at 8.89 ppm that possessed a broad line width and corresponded in intensity to a single proton. These reagents were also used successfully for the identification of the aldimine 4'-H resonance in the mitochondrial isoenzyme. In contrast to the cytosolic isoenzyme whose resonance for the 4'-H did not show any detectable change in chemical shift with pH, the corresponding resonance in the mitochondrial isoenzyme exhibited pH-dependent chemical shift change (8.84 ppm at pH 5 and 8.67 ppm at pH 8) with a pK value of 6.3, reflecting the interisozymic difference in the microenvironment provided for the internal aldimine. Validity of the signal assignment was further shown by the two findings: the resonance assigned to the 4'-H emerged upon conversion of the pyridoxamine into the pyridoxal form, and the resonance appeared upon reconstitution of the apoenzyme with [4'-1H]pyridoxal phosphate but not with [4'-2H]pyridoxal phosphate.
pubmed:language
eng
pubmed:journal
pubmed:citationSubset
IM
pubmed:chemical
pubmed:status
MEDLINE
pubmed:month
Apr
pubmed:issn
0006-2960
pubmed:author
pubmed:issnType
Print
pubmed:day
22
pubmed:volume
25
pubmed:owner
NLM
pubmed:authorsComplete
Y
pubmed:pagination
1917-25
pubmed:dateRevised
2006-11-15
pubmed:meshHeading
pubmed:year
1986
pubmed:articleTitle
Identification of coenzyme aldimine proton in 1H NMR spectra of pyridoxal 5'-phosphate dependent enzymes: aspartate aminotransferase isoenzymes.
pubmed:publicationType
Journal Article, Comparative Study, Research Support, Non-U.S. Gov't