Linked Life Data

11162121

Source:http://linkedlifedata.com/resource/pubmed/id/11162121

Statements in which the resource exists as a subject.
PredicateObject
rdf:type
lifeskim:mentions
pubmed:issue
5
pubmed:dateCreated
2001-2-22
pubmed:abstractText
We have measured the effect of temperature and denaturant concentration on the rate of intrachain diffusion in an unfolded protein. After photodissociating a ligand from the heme iron of unfolded horse cytochrome c, we use transient optical absorption spectroscopy to measure the time scale of the diffusive motions that bring the heme, located at His18, into contact with its native ligand, Met80. Measuring the rate at which this 62 residue intrachain loop forms under both folding and unfolding conditions, we find a significant effect of denaturant on the chain dynamics. The diffusion of the chain accelerates as denaturant concentration decreases, with the contact formation rate approaching a value near approximately 6x10(5) s(-1) in the absence of denaturant. This result agrees well with an extrapolation from recent loop formation measurements in short synthetic peptides. The temperature dependence of the rate of contact formation indicates an Arrhenius activation barrier, Ea approximately 20 kJ/mol, at high denaturant concentrations, comparable to what is expected from solvent viscosity effects alone. Although Ea increases by several kBT as denaturant concentration decreases, the overall rate of diffusion nevertheless increases. These results indicate that inter-residue energetic interactions do not control conformational diffusion in unfolded states, even under folding conditions.
pubmed:language
eng
pubmed:journal
pubmed:citationSubset
IM
pubmed:chemical
pubmed:status
MEDLINE
pubmed:month
Feb
pubmed:issn
0022-2836
pubmed:author
pubmed:issnType
Print
pubmed:day
2
pubmed:volume
305
pubmed:owner
NLM
pubmed:authorsComplete
Y
pubmed:pagination
1161-71
pubmed:dateRevised
2006-11-15
pubmed:meshHeading
pubmed:year
2001
pubmed:articleTitle
Rate of intrachain contact formation in an unfolded protein: temperature and denaturant effects.
pubmed:affiliation
Physics Department, University of Florida, PO Box 118440, Gainesville, FL 32611, USA. sjhagen@ufl.edu
pubmed:publicationType
Journal Article, Research Support, U.S. Gov't, Non-P.H.S., Research Support, Non-U.S. Gov't