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Titolo:
Assignment of the 1511 cm(-1) UV resonance Raman marker band of hemoglobinto tryptophan
Autore:
Zhao, XJ; Chen, RP; Raj, V; Spiro, TG;
Indirizzi:
Princeton Univ, Dept Chem, Princeton, NJ 08544 USA Princeton Univ Princeton NJ USA 08544 Dept Chem, Princeton, NJ 08544 USA
Titolo Testata:
BIOPOLYMERS
fascicolo: 3, volume: 62, anno: 2001,
pagine: 158 - 162
SICI:
0006-3525(2001)62:3<158:AOT1CU>2.0.ZU;2-D
Fonte:
ISI
Lingua:
ENG
Soggetto:
QUATERNARY STRUCTURE; SPECTROSCOPY; TYROSINE; MUTANTS; ALLOSTERY; RESIDUES;
Keywords:
UV resonance Raman spectroscopy; marker band; hemoglobin; tryptophan;
Tipo documento:
Article
Natura:
Periodico
Settore Disciplinare:
Life Sciences
Citazioni:
20
Recensione:
Indirizzi per estratti:
Indirizzo: Spiro, TG Princeton Univ, Dept Chem, Princeton, NJ 08544 USA Princeton Univ Princeton NJ USA 08544 , Princeton, NJ 08544 USA
Citazione:
X.J. Zhao et al., "Assignment of the 1511 cm(-1) UV resonance Raman marker band of hemoglobinto tryptophan", BIOPOLYMERS, 62(3), 2001, pp. 158-162

Abstract

New UV resonance Raman (UVRR) data provide convincing evidence that a characteristic 1511 cm(-1) band in the T - R difference spectra of hemoglobin is due to the overtone of the Trp W18 fundamental at 756 cm(-1). Measured isotope shifts for 2-H and 15-N substitution at the indole NH group are twiceas large for the 1511 cm-l band as for W18, and the 1511 cm(-1) intensity scales with that of W18 in the difference spectrum. Moreover, the UVRR excitation profile of the 1511 cm(-1) band tracks that of another tryptophan band, W16. Both are redshifted in hemoglobin, relative to aqueous tryptophan,reflecting H bonding within a hydrophobic environment in the protein. The 2 xW18 assignment had been thrown into question by the observation of remnant 1511 cml intensity in the T - R spectra of hemoglobin labeled with tryptophan-d(5), a substitution that shifts W18 over 50 cm(-1). However, reexamination of the data suggests that this remnant intensity may result from a subtraction artifact arising from the downshift of another difference band, W3, from 1549 cm(-1) in unlabeled protein to 1522 cm(-1) in labeled protein. Restoration of the 2xW18 assignment establishes that the 1511 cm(-1) difference band, which is a useful indicator of the extent of T-state formationin hemoglobin, arises from the same residue, Trp beta 37, that gives rise to essentially all of the T - R signal from tryptophan. (C) 2001 John Wiley& Sons, Inc.

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Documento generato il 24/09/20 alle ore 21:34:47