Linked Life Data

19547959

Source:http://linkedlifedata.com/resource/pubmed/id/19547959

Statements in which the resource exists as a subject.
PredicateObject
rdf:type
lifeskim:mentions
pubmed:issue
3
pubmed:dateCreated
2009-7-23
pubmed:abstractText
S-Adenosylhomocysteine-hydrolase (AdoHcy-hydrolase) catalyzes the reversible hydrolysis of S-adenosylhomocysteine (AdoHcy) to adenosine (Ado) and homocysteine (Hcy). Since Ado competes with cAMP at the high affinity-binding site of the enzyme, we determined the effect of cAMP on enzyme activity and its binding characteristics to purified AdoHcy-hydrolase from bovine kidney in its native, in its fully oxidized (NAD(+)), and in its fully reduced (NADH) form. cAMP (10 micromol/l) enhanced the hydrolytic activity of native AdoHcy-hydrolase by 35%, whereas the activity of the enzyme in its NAD(+) form was not stimulated by cAMP. In contrast to azido-Ado, binding of azido-cAMP did not inhibit the enzymatic activity of AdoHcy-hydrolase. Furthermore, cAMP did not prevent the Ado induced inhibition of the AdoHcy hydrolysis. Saturation binding experiments with the three different forms of AdoHcy-hydrolase, native, NAD(+), and NADH showed only one binding site with high affinity. This binding site was identified after photoaffinity labeling of the enzyme with 8-azido-[2-(3)H]-cAMP. One photolabeled peptide was isolated as Trp(310)-Val(325) from each AdoHcy-hydrolase from native, NAD(+), and NADH. The cAMP-labeled peptide is located in the NAD-binding domain of AdoHcy-hydrolase. In conclusion, our data show that the cAMP-binding site at the AdoHcy-hydrolase is independent of the NAD(+)/NADH ratio of the enzyme and is identical with the high affinity-binding site of Ado. Moreover, cAMP did not interact with the catalytic site of AdoHcy-hydrolase and did not act as an allosteric effector for the AdoHcy-hydrolase.
pubmed:language
eng
pubmed:journal
pubmed:citationSubset
IM
pubmed:chemical
pubmed:status
MEDLINE
pubmed:month
Sep
pubmed:issn
1432-1912
pubmed:author
pubmed:issnType
Electronic
pubmed:volume
380
pubmed:owner
NLM
pubmed:authorsComplete
Y
pubmed:pagination
215-22
pubmed:meshHeading
pubmed:year
2009
pubmed:articleTitle
Determinants for the cAMP-binding site at the S-adenosylhomocysteine-hydrolase.
pubmed:affiliation
Department of Experimental and Clinical Pharmacology and Toxicology, Faculty of Medicine, University of Tübingen, Wilhelmstrasse 56, Tübingen, Germany. doris.kloor@uni-tuebingen.de
pubmed:publicationType
Journal Article, Research Support, Non-U.S. Gov't