Linked Life Data

8620862

Source:http://linkedlifedata.com/resource/pubmed/id/8620862

Statements in which the resource exists as a subject.
PredicateObject
rdf:type
lifeskim:mentions
pubmed:issue
1
pubmed:dateCreated
1996-6-19
pubmed:abstractText
Heat-induced modifications in the tertiary and quaternary structure of beta-lactoglobulin were followed at neutral pH for the protein at high temperature and for the protein that was heated and cooled. Fast changes in the environment of aromatic amino acids were apparent from near-ultraviolet-CD spectra of the heated protein and their intensity increased with increasing temperature. These modifications were irreversible only at temperatures higher than 65-70 degrees C. Addition of iodoacetamide during the heating/cooling cycle greatly reduced the extent of irreversible modification of the tertiary structure of the protein. Reaction of the native beta-lactoglobulin dimer with iodoacetamide or dithiobis(2-nitrobenzoic acid) was only observed upon heating at temperatures higher than 40 degrees C and resulted in progressive reaction of the unique sulfhydryl group in each of the two protein monomers. The sulfhydryl reagents induced release of a monomeric protein species that was no longer able to aggregate to the native dimeric form or to sequentially form polymers as found in the protein after heating at high temperature. Dimer dissociation was identified as the rate-limiting step in the reaction of beta-lactoglobulin with sulfhydryl reagents. It occurred at temperatures much lower than those required for appreciable modification of the tertiary structure of the protein, and had an extremely high activation energy (Ea = 213 kJ/mol). These results are compared with other published data, and a general mechanism for the formation of early reactive species in heat-treated beta-lactoglobulin at neutral pH is proposed which stresses the relevant role of a highly hydrophobic, molten-globule-like free monomer that has an exposed sulfhydryl group on its surface.
pubmed:language
eng
pubmed:journal
pubmed:citationSubset
IM
pubmed:chemical
pubmed:status
MEDLINE
pubmed:month
Apr
pubmed:issn
0014-2956
pubmed:author
pubmed:issnType
Print
pubmed:day
1
pubmed:volume
237
pubmed:owner
NLM
pubmed:authorsComplete
Y
pubmed:pagination
106-12
pubmed:dateRevised
2008-11-21
pubmed:meshHeading
pubmed:year
1996
pubmed:articleTitle
Modifications occur at different structural levels during the heat denaturation of beta-lactoglobulin.
pubmed:affiliation
Dipartimento di Scienze Molecolari Agroalimentari, Università di Milano, Italy.
pubmed:publicationType
Journal Article, Research Support, Non-U.S. Gov't