Source:http://linkedlifedata.com/resource/pubmed/id/11432860
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| Predicate | Object |
|---|---|
| rdf:type | |
| lifeskim:mentions | |
| pubmed:issue |
36
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| pubmed:dateCreated |
2001-9-4
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| pubmed:abstractText |
Angiotensin (Ang) I-converting enzyme (ACE) is a Zn(2+) metalloprotease with two homologous catalytic domains. Both the N- and C-terminal domains are peptidyl dipeptidases. Hydrolysis by ACE of its decapeptide substrate Ang I is increased by Cl(-), but the molecular mechanism of this regulation is unclear. A search for single substitutions to Gln among all conserved basic residues (Lys/Arg) in human ACE C-domain identified R1098Q as the sole mutant that lacked Cl(-) dependence. Cl(-) dependence is also lost when the equivalent Arg in the N-domain, Arg(500), is substituted with Gln. The Arg(1098) to Lys substitution reduced Cl(-) binding affinity by approximately 100-fold. In the absence of Cl(-), substrate binding affinity (1/K(m)) of and catalytic efficiency (k(cat)/K(m)) for Ang I hydrolysis are increased 6.9- and 32-fold, respectively, by the Arg(1098) to Gln substitution, and are similar (<2-fold difference) to the respective wild-type C-domain catalytic constants in the presence of optimal [Cl(-)]. The Arg(1098) to Gln substitution also eliminates Cl(-) dependence for hydrolysis of tetrapeptide substrates, but activity toward these substrates is similar to that of the wild-type C-domain in the absence of Cl(-). These findings indicate that: 1) Arg(1098) is a critical residue of the C-domain Cl(-)-binding site and 2) a basic side chain is necessary for Cl(-) dependence. For tetrapeptide substrates, the inability of R1098Q to recreate the high affinity state generated by the Cl(-)-C-domain interaction suggests that substrate interactions with the enzyme-bound Cl(-) are much more important for the hydrolysis of short substrates than for Ang I. Since Cl(-) concentrations are saturating under physiological conditions and Arg(1098) is not critical for Ang I hydrolysis, we speculate that the evolutionary pressure for the maintenance of the Cl(-)-binding site is its ability to allow cleavage of short cognate peptide substrates at high catalytic efficiencies.
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| pubmed:language |
eng
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| pubmed:journal | |
| pubmed:citationSubset |
IM
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| pubmed:chemical |
http://linkedlifedata.com/resource/pubmed/chemical/Arginine,
http://linkedlifedata.com/resource/pubmed/chemical/Chlorine,
http://linkedlifedata.com/resource/pubmed/chemical/Glutamine,
http://linkedlifedata.com/resource/pubmed/chemical/Peptides,
http://linkedlifedata.com/resource/pubmed/chemical/Peptidyl-Dipeptidase A,
http://linkedlifedata.com/resource/pubmed/chemical/Recombinant Proteins,
http://linkedlifedata.com/resource/pubmed/chemical/Sodium Chloride
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| pubmed:status |
MEDLINE
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| pubmed:month |
Sep
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| pubmed:issn |
0021-9258
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| pubmed:author | |
| pubmed:issnType |
Print
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| pubmed:day |
7
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| pubmed:volume |
276
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| pubmed:owner |
NLM
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| pubmed:authorsComplete |
Y
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| pubmed:pagination |
33518-25
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| pubmed:dateRevised |
2004-11-17
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| pubmed:meshHeading |
pubmed-meshheading:11432860-Allosteric Site,
pubmed-meshheading:11432860-Amino Acid Sequence,
pubmed-meshheading:11432860-Animals,
pubmed-meshheading:11432860-Arginine,
pubmed-meshheading:11432860-Binding Sites,
pubmed-meshheading:11432860-COS Cells,
pubmed-meshheading:11432860-Catalysis,
pubmed-meshheading:11432860-Catalytic Domain,
pubmed-meshheading:11432860-Chlorine,
pubmed-meshheading:11432860-Dose-Response Relationship, Drug,
pubmed-meshheading:11432860-Enzyme Activation,
pubmed-meshheading:11432860-Glutamine,
pubmed-meshheading:11432860-Humans,
pubmed-meshheading:11432860-Kinetics,
pubmed-meshheading:11432860-Molecular Sequence Data,
pubmed-meshheading:11432860-Peptides,
pubmed-meshheading:11432860-Peptidyl-Dipeptidase A,
pubmed-meshheading:11432860-Protein Binding,
pubmed-meshheading:11432860-Protein Structure, Tertiary,
pubmed-meshheading:11432860-Recombinant Proteins,
pubmed-meshheading:11432860-Sequence Homology, Amino Acid,
pubmed-meshheading:11432860-Sodium Chloride,
pubmed-meshheading:11432860-Transfection
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| pubmed:year |
2001
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| pubmed:articleTitle |
Arg(1098) is critical for the chloride dependence of human angiotensin I-converting enzyme C-domain catalytic activity.
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| pubmed:affiliation |
Enzyme Research Unit, Victor Chang Cardiac Research Institute, Sydney, New South Wales 2010, Australia.
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| pubmed:publicationType |
Journal Article
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