Linked Life Data

9851707

Source:http://linkedlifedata.com/resource/pubmed/id/9851707

Statements in which the resource exists as a subject.
PredicateObject
rdf:type
lifeskim:mentions
pubmed:issue
1
pubmed:dateCreated
1998-12-28
pubmed:abstractText
The small heat-shock protein, alpha-crystallin, has chaperone ability whereby it stabilises proteins under stress conditions. In this study, alterations in the structure of alpha-crystallin during its interaction with a variety of substrate proteins (insulin, alpha-lactalbumin, ovotransferrin and serum albumin) under stress conditions have been examined using visible absorption, 31P-NMR and 1H-NMR and fluorescence spectroscopy. The fluorescence and 31P-NMR data imply that during the chaperone action of alpha-crystallin under reducing conditions, there is a slight increase in hydrophilicity of its N-terminal region and an alteration in flexibility of its C-terminal region, but overall, alpha-crystallin does not undergo a gross structural change. The fluorescence data suggest that substrate proteins interact with alpha-crystallin in a molten globule or intermediately folded state. The same conclusion is made from 1H-NMR spectroscopic monitoring of the interaction of alpha-crystallin with substrate proteins, e.g. the insulin B chain. The stoichiometry of interaction between alpha-crystallin and the various substrate proteins reveals that steric factors are important in determining the efficiency of interaction between the two proteins, i.e. on a molar subunit basis, alpha-crystallin is a more efficient chaperone protein with smaller substrate proteins. Comparison is also made between the high-molecular-mass (HMM) complexes formed between alpha-crystallin and ovotransferrin when reduced and heat stressed. Under heating conditions, fluorescence spectroscopy indicates that the HMM complex has a greater exposure of hydrophobicity to solution than that formed by reduction. Furthermore, in interacting with heated ovotransferrin, the C-terminal extension of the alphaB-crystallin subunit preferentially loses its flexibility suggesting that it is involved in stabilising bound ovotransferrin. By contrast, this extension is only partially reduced in flexibility in the HMM complex formed after reduction of ovotransferrin. The functional role of the C-terminal extensions in the chaperone action and the overall quaternary structure of alpha-crystallin is discussed.
pubmed:language
eng
pubmed:journal
pubmed:citationSubset
IM
pubmed:chemical
pubmed:status
MEDLINE
pubmed:month
Nov
pubmed:issn
0014-2956
pubmed:author
pubmed:issnType
Print
pubmed:day
15
pubmed:volume
258
pubmed:owner
NLM
pubmed:authorsComplete
Y
pubmed:pagination
170-83
pubmed:dateRevised
2007-7-23
pubmed:meshHeading
pubmed:year
1998
pubmed:articleTitle
Structural alterations of alpha-crystallin during its chaperone action.
pubmed:affiliation
Department of Chemistry, The University of Wollongong, NSW, Australia.
pubmed:publicationType
Journal Article, Research Support, Non-U.S. Gov't