Linked Life Data

2001360

Source:http://linkedlifedata.com/resource/pubmed/id/2001360

Statements in which the resource exists as a subject.
PredicateObject
rdf:type
lifeskim:mentions
pubmed:issue
10
pubmed:dateCreated
1991-4-17
pubmed:abstractText
The peptides generated from the degradation of the oxidized B chain of bovine insulin by the multiproteinase complex macropain (proteasome) have been analyzed by reverse-phase peptide mapping and identified by N-terminal amino acid sequencing and composition analysis. Six of the 29 peptide bonds in the insulin B chain were found to be rapidly cleaved by macropain. The catalytic center that cleaves the Gln4-His5 bond could be distinguished from the center or centers that cleave the other preferred bonds by its specific susceptibility to inhibition by leupeptin, antipain, chymostatin, and pentamidine, suggesting that macropain utilizes at least two distinct catalytic centers for the degradation of this model polypeptide. The same effectors simultaneously enhance the rate of cleavage at the other susceptible sites in insulin B. The quantitative characteristics of this effect indicate that different catalytic centers of the complex may be functionally coupled, possibly by an allosteric mechanism or possibly by a mechanism in which binding to the catalytic centers is preceded by a rate-limiting binding of the substrate to a site or sites on the enzyme distinct from the catalytic centers. The kinetics of insulin B chain degradation indicate that macropain can catalyze sequential hydrolysis of peptide bonds in a single substrate molecule via a reaction pathway that involves channeling of peptide intermediates between different catalytic centers within the multienzyme complex. This capacity for channeling may confer potential physiological advantages of increasing the efficiency of amino acid recycling and reducing the pool sizes of peptide intermediates that are generated during the degradation of polypeptides in the intracellular milieu.
pubmed:language
eng
pubmed:journal
pubmed:citationSubset
IM
pubmed:chemical
pubmed:status
MEDLINE
pubmed:month
Mar
pubmed:issn
0006-2960
pubmed:author
pubmed:issnType
Print
pubmed:day
12
pubmed:volume
30
pubmed:owner
NLM
pubmed:authorsComplete
Y
pubmed:pagination
2725-34
pubmed:dateRevised
2011-11-17
pubmed:meshHeading
pubmed:year
1991
pubmed:articleTitle
Degradation of oxidized insulin B chain by the multiproteinase complex macropain (proteasome).
pubmed:affiliation
Department of Biochemistry, University of Texas Southwestern Medical Center, Dallas 75235.
pubmed:publicationType
Journal Article, Research Support, Non-U.S. Gov't