Linked Life Data

7540822

Source:http://linkedlifedata.com/resource/pubmed/id/7540822

Statements in which the resource exists as a subject.
PredicateObject
rdf:type
lifeskim:mentions
pubmed:issue
1
pubmed:dateCreated
1995-7-27
pubmed:abstractText
The ability of NG-nitro-L-arginine (NNA) and NG-methyl-L-arginine (NMMA) to inactivate native neuronal, endothelial cell, and macrophage nitric oxide synthases (nNOS, eNOS, and iNOS, respectively) was investigated. Each NOS isozyme (plus cofactors) was preincubated with either NNA or NMMA and then assayed for remaining activity by measuring the conversion of labeled L-arginine to labeled L-citrulline. Consistent with previous reports (Olken, N. M., et al., Biochem. Biophys. Res. Commun. 177, 828-833, 1991), NMMA was a mechanism-based irreversible inhibitor of iNOS, exhibiting time- and concentration-dependent inactivation of iNOS with a KI equal to 2.6 microM and a kinact equal to 0.042 min-1. When assayed without a preincubation period, NMMA exhibited typical reversible inhibition of iNOS (Ki = 3.9 microM). NMMA also reversibly inhibited nNOS and the eNOS with Ki equal to 0.65 and 0.7 microM, respectively. However, NMMA did not inactivate eNOS at concentrations up to 10 microM. In the presence, but not the absence, of 4 microM tetrahydrobiopterin, NMMA inactivated nNOS with a kinact equal to 0.022 min-1 and a KI equal to 2.0 microM. Since NNA did not inactivate iNOS at concentrations up to 25 microM, NNA is strictly a reversible inhibitor of iNOS (Ki = 8.1 microM). Neuronal NOS and eNOS, however, were rapidly inactivated by NNA with kintact equal to 0.083 and 0.047 min-1 and KI equal to 0.09 and 0.02 microM, respectively, when preincubated with NNA. Tetrahydrobiopterin did not affect the rate of inactivation of nNOS by NNA. In all cases, L-arginine protected against inactivation, suggesting that inactivation occurs at or near the active site. Thus, inactivation of the three NOS isozymes with NMMA and NNA reveals active-site differences between the isoforms.
pubmed:language
eng
pubmed:journal
pubmed:citationSubset
IM
pubmed:chemical
pubmed:status
MEDLINE
pubmed:month
Jun
pubmed:issn
0003-9861
pubmed:author
pubmed:issnType
Print
pubmed:day
20
pubmed:volume
320
pubmed:owner
NLM
pubmed:authorsComplete
Y
pubmed:pagination
170-6
pubmed:dateRevised
2006-11-15
pubmed:meshHeading
pubmed:year
1995
pubmed:articleTitle
N-nitro-L-arginine and N-monomethyl-L-arginine exhibit a different pattern of inactivation toward the three nitric oxide synthases.
pubmed:affiliation
Fisons Pharmaceuticals, Biology Department, Rochester, New York 14603, USA.
pubmed:publicationType
Journal Article, In Vitro