Linked Life Data

1761513

Source:http://linkedlifedata.com/resource/pubmed/id/1761513

Statements in which the resource exists as a subject.
PredicateObject
rdf:type
lifeskim:mentions
pubmed:issue
2
pubmed:dateCreated
1992-2-11
pubmed:abstractText
Dipeptidylcarboxypeptidase, endopeptidase, and carboxypeptidase activities of rat liver cathepsin B were investigated using soluble denatured protein substrates, reduced and S-(3-trimethylammonio)propylated proteins and their derivatives. It was found that the soluble denatured proteins were degraded mainly by the dipeptidylcarboxypeptidase activity and in a few cases by the endopeptidase and carboxypeptidase activities. The eipeptidylcarboxypeptidase activity showed broad substrate specificity with broad pH optimum at 4-6. A peptide having the alpha-carboxyl group amidated with methylamine could also be a good substrate for this activity. These results suggest that this activity is dependent not upon the dissociated alpha-carboxyl group at the P2' site but upon the hydrogen-bonding abilities of the alpha-imino moiety and the protonated or amidated alpha-carboxyl moiety at P2'. On the other hand, the endopeptidase and carboxypeptidase activities were observed in a few cases, suggesting that special amino acid sequences in the substrates are responsible for these activities. These activities showed sharp pH optima at 6 and seemed to prefer basic amino acid residues at P1 site. Therefore, we suppose that cathepsin B has a carboxyl group with a pKa of about 5.5 at the S1 subsite which more effectively interacts with a positive charge at the P1 site of the substrate at pH 6 than at pH 5. Based on these results, a model of the binding subsites of this enzyme is proposed.
pubmed:language
eng
pubmed:journal
pubmed:citationSubset
IM
pubmed:chemical
pubmed:status
MEDLINE
pubmed:month
Aug
pubmed:issn
0021-924X
pubmed:author
pubmed:issnType
Print
pubmed:volume
110
pubmed:owner
NLM
pubmed:authorsComplete
Y
pubmed:pagination
179-88
pubmed:dateRevised
2007-12-19
pubmed:meshHeading
pubmed:year
1991
pubmed:articleTitle
Multiple proteolytic action of rat liver cathepsin B: specificities and pH-dependences of the endo- and exopeptidase activities.
pubmed:affiliation
Faculty of Pharmaceutical Science, Kyushu University, Fukuoka.
pubmed:publicationType
Journal Article, Research Support, Non-U.S. Gov't