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| Predicate | Object |
|---|---|
| rdf:type | |
| lifeskim:mentions | |
| pubmed:issue |
8
|
| pubmed:dateCreated |
1991-4-17
|
| pubmed:abstractText |
We have modified the single cysteine residue of alpha 1-protease inhibitor (alpha 1-PI) with HgCl2, methylmethane thiosulfonate, oxidized glutathione (GSSG), and N-(1-anilinonaphthyl-4)maleimide (ANM). Whereas native alpha 1-PI combines rapidly and quasi-irreversibly with neutrophil elastase, the thiol-modified alpha 1-PI derivatives are dissociable reversible competitive inhibitors of the enzyme, with values of Ki in the range of 6-7 nM. Removal of the thiol modifications restores the rapid irreversible mode of inhibition. Once native alpha 1-PI has combined with neutrophil elastase, the enzyme-inhibitor complex retains a reactive thiol group, but the two proteins can no longer be dissociated by subsequent reaction with ANM, even after exposure to sodium dodecyl sulfate-polyacrylamide gel electrophoresis. From kinetic measurements of fluorescence, ANM-modified alpha 1-PI combines with neutrophil elastase via an apparent biomolecular process with a second order rate constant on the order of 10(5) M-1 S-1. We estimate a dissociation rate constant on the order of 10(-3) S-1. The emission of ANM-modified alpha 1-PI is increased in intensity and blue shifted from the maximum in ANM-modified cysteine, consistent with a predominantly nonpolar environment. Association with neutrophil elastase results in an additional blue shift with further increase in intensity, consistent with a further decrease in polarity of the environment of the cysteine. Modification with methylmethane thiosulfonate or GSSG results in a small decrease in quantum yield and a red shift in the tryptophan emission spectrum of the modified inhibitor, suggestive of increased polarity of the environment of at least 1 of the 2 tryptophan residues in alpha 1-PI. These changes are reversed by dithiothreitol and are consistent with a conformational change which transforms the inhibitory activity from a rapid, irreversible mode in native alpha 1-PI to a dissociable competitive mode in the mixed disulfide derivatives.
|
| pubmed:grant | |
| pubmed:language |
eng
|
| pubmed:journal | |
| pubmed:citationSubset |
IM
|
| pubmed:chemical | |
| pubmed:status |
MEDLINE
|
| pubmed:month |
Mar
|
| pubmed:issn |
0021-9258
|
| pubmed:author | |
| pubmed:issnType |
Print
|
| pubmed:day |
15
|
| pubmed:volume |
266
|
| pubmed:owner |
NLM
|
| pubmed:authorsComplete |
Y
|
| pubmed:pagination |
5279-85
|
| pubmed:dateRevised |
2007-11-14
|
| pubmed:meshHeading |
pubmed-meshheading:2002060-Binding, Competitive,
pubmed-meshheading:2002060-Electrophoresis, Polyacrylamide Gel,
pubmed-meshheading:2002060-Humans,
pubmed-meshheading:2002060-Kinetics,
pubmed-meshheading:2002060-Leukocyte Elastase,
pubmed-meshheading:2002060-Pancreatic Elastase,
pubmed-meshheading:2002060-Spectrometry, Fluorescence,
pubmed-meshheading:2002060-Sulfhydryl Compounds,
pubmed-meshheading:2002060-alpha 1-Antitrypsin
|
| pubmed:year |
1991
|
| pubmed:articleTitle |
Reversible inhibition of neutrophil elastase by thiol-modified alpha-1 protease inhibitor.
|
| pubmed:affiliation |
Department of Biochemistry and Cell Biology, State University of New York, Stony Brook 11794.
|
| pubmed:publicationType |
Journal Article,
Research Support, U.S. Gov't, P.H.S.,
Research Support, Non-U.S. Gov't
|