Linked Life Data

18510974

Source:http://linkedlifedata.com/resource/pubmed/id/18510974

Statements in which the resource exists as a subject.
PredicateObject
rdf:type
lifeskim:mentions
pubmed:issue
6
pubmed:dateCreated
2008-5-30
pubmed:abstractText
Insect chymotrypsins are distinctively sensitive to plant protein inhibitors, suggesting that they differ in subsite architecture and hence in substrate specificities. Purified digestive chymotrypsins from insects of three different orders were assayed with internally quenched fluorescent oligopeptides with three different amino acids at P1 (Tyr, Phe, and Leu) and 13 amino acid replacements in positions P1', P2, and P3. The binding energy (DeltaG(s), calculated from K(m) values) and the activation energy (DeltaG(T)++, determined from k(cat)/K(m) values) were calculated. The hydrophobicities of each subsite were calculated from the efficiency of hydrolysis of the different amino acid replacements at that subsite. The results showed that except for S1, the other subsites (S2, S3, and S1') vary among chymotrypsins. This result contrasts with insect trypsin data that revealed a trend along evolution, putatively associated with resistance to plant inhibitors. In spite of those differences, the data suggested that in lepidopteran chymotrypsins S2 and S1' bind the substrate ground state, whereas only S1' binds the transition state, supporting aspects of the present accepted mechanism of catalysis.
pubmed:language
eng
pubmed:journal
pubmed:citationSubset
IM
pubmed:chemical
pubmed:status
MEDLINE
pubmed:month
Jun
pubmed:issn
0965-1748
pubmed:author
pubmed:issnType
Print
pubmed:volume
38
pubmed:owner
NLM
pubmed:authorsComplete
Y
pubmed:pagination
628-33
pubmed:dateRevised
2010-11-18
pubmed:meshHeading
pubmed:year
2008
pubmed:articleTitle
Subsite substrate specificity of midgut insect chymotrypsins.
pubmed:affiliation
Departamento de Bioquímica, Instituto de Química, Universidade de São Paulo, São Paulo, Brazil.
pubmed:publicationType
Journal Article, Research Support, Non-U.S. Gov't