Linked Life Data

14726205

Source:http://linkedlifedata.com/resource/pubmed/id/14726205

Statements in which the resource exists as a subject.
PredicateObject
rdf:type
lifeskim:mentions
pubmed:issue
1
pubmed:dateCreated
2004-1-16
pubmed:abstractText
The gene encoding an esterase (PsyEst) of Psychrobacter sp. Ant300, a psychrophilic bacterium isolated from Antarctic soil, was cloned, sequenced, and expressed in Escherichia coli. PsyEst, which is a member of hormone-sensitive lipase (HSL) group of the lipase/esterase family, is a cold-active, themolabile enzyme with high catalytic activity at low temperatures (5-25 degrees C), low activation energy (e.g., 4.6 kcal/mol for hydrolysis of p-nitrophenyl butyrate), and a t(1/2) value of 16 min for thermal inactivation during incubation at 40 degrees C and pH 7.9. A three-dimensional structural model of PsyEst predicted that Gly(244) was located in the loop near the active site of PsyEst and that substitution of this amino-acid residue by proline should potentially rigidify the active-site environment of the enzyme. Thus, we introduced the Gly(244)-->Pro substitution into the enzyme. Stability studies showed that the t(1/2) value for thermal inactivation of the mutant during incubation at 40 degrees C and pH 7.9 was 11.6 h, which was significantly greater than that of the wild-type enzyme. The k(cat)/K(m) value of the mutant was lower for all substrates examined than the value of the wild type. Moreover, this amino-acid substitution caused a shift of the acyl-chain length specificity of the enzyme toward higher preference for short-chain fatty acid esters. All of these observations could be explained in terms of a decrease in active-site flexibility brought about by the mutation and were consistent with the hypothesis that cold activity and thermolability arise from local flexibility around the active site of the enzyme.
pubmed:language
eng
pubmed:journal
pubmed:citationSubset
IM
pubmed:chemical
pubmed:status
MEDLINE
pubmed:month
Jan
pubmed:issn
0006-3002
pubmed:author
pubmed:issnType
Print
pubmed:day
14
pubmed:volume
1696
pubmed:owner
NLM
pubmed:authorsComplete
Y
pubmed:pagination
59-65
pubmed:dateRevised
2008-11-21
pubmed:meshHeading
pubmed:year
2004
pubmed:articleTitle
Cold-active esterase from Psychrobacter sp. Ant300: gene cloning, characterization, and the effects of Gly-->Pro substitution near the active site on its catalytic activity and stability.
pubmed:affiliation
Laboratory of Microbial Biochemistry, Institute for Chemical Research, Kyoto University, Uji, Kyoto-Fu, Kyoto 611-0011, Japan.
pubmed:publicationType
Journal Article, Comparative Study, Research Support, Non-U.S. Gov't