Linked Life Data

16313176

Source:http://linkedlifedata.com/resource/pubmed/id/16313176

Statements in which the resource exists as a subject.
PredicateObject
rdf:type
lifeskim:mentions
pubmed:issue
48
pubmed:dateCreated
2005-11-29
pubmed:abstractText
Early events in the unfolding of apomyoglobin are studied with time-resolved ultraviolet resonance Raman (UVRR) spectroscopy coupled to a laser-induced temperature jump (T-jump). The UVRR spectra provide simultaneous probes of the aromatic side-chain environment and the amide backbone conformation. The amide bands reveal helix melting, with relaxation times of 70 and 16 micros at pH 5.5 and 4, respectively, in reasonable agreement with previously reported amide I' FTIR/T-jump relaxations (132 and 14 micros at pD 5.5 and 3). The acceleration at pH 4 is consistent with destabilization of the hydrophobic AGH core of the protein via protonation of a pair of buried histidines. The same relaxation times are found for intensity loss by the phenylalanine F12 band, signaling solvent exposure of the phenyl rings. There are seven Phe residues, distributed throughout the protein; they produce a global response, parallel to helix melting. Relaxation of the tryptophan W16 intensity also parallels helix melting at pH 5.5 but is twice as fast, 7 micros, at pH 4. The pH 5.5 signal arises from Trp 7, which is partially solvent-exposed, while the pH 4 signal arises from the buried Trp 14. Thus, Trp 14 is exposed to the solvent prior to helix melting of the AGH core, suggesting initial displacement of the A helix, upon which Trp 14 resides. All of the UVRR signals show a prompt response, within the instrument resolution (approximately 60 ns), which accounts for half of the total relaxation amplitude. This response is attributed to solvent penetration into the protein, possibly convoluted with melting of hydrated helix segments.
pubmed:grant
pubmed:language
eng
pubmed:journal
pubmed:citationSubset
IM
pubmed:chemical
pubmed:status
MEDLINE
pubmed:month
Dec
pubmed:issn
0006-2960
pubmed:author
pubmed:issnType
Print
pubmed:day
6
pubmed:volume
44
pubmed:owner
NLM
pubmed:authorsComplete
Y
pubmed:pagination
15734-42
pubmed:dateRevised
2007-11-14
pubmed:meshHeading
pubmed:year
2005
pubmed:articleTitle
Early events in apomyoglobin unfolding probed by laser T-jump/UV resonance Raman spectroscopy.
pubmed:affiliation
Department of Chemistry, Princeton University, Princeton, New Jersey 08544, USA.
pubmed:publicationType
Journal Article, Research Support, N.I.H., Extramural