Catalogo Articoli (Spogli Riviste)

OPAC HELP

Titolo:
F-19 NMR RELAXATION STUDIES ON 5-FLUOROTRYPTOPHAN-LABELED AND TETRADEUTERO-5-FLUOROTRYPTOPHAN-LABELED ESCHERICHIA-COLI GLUCOSE GALACTOSE RECEPTOR/
Autore:
LUCK LA; VANCE JE; OCONNELL TM; LONDON RE;
Indirizzi:
NIEHS,MOL BIOPHYS LAB,NIH,POB 12233 RES TRIANGLE PK NC 27709 NIEHS,MOL BIOPHYS LAB,NIH RES TRIANGLE PK NC 27709
Titolo Testata:
Journal of biomolecular NMR
fascicolo: 4, volume: 7, anno: 1996,
pagine: 261 - 272
SICI:
0925-2738(1996)7:4<261:FNRSO5>2.0.ZU;2-J
Fonte:
ISI
Lingua:
ENG
Soggetto:
NUCLEAR-MAGNETIC-RESONANCE; GALACTOSE CHEMOSENSORY RECEPTOR; D-LACTATE DEHYDROGENASE; ESCHERICHIA-COLI; BINDING-PROTEIN; DIHYDROFOLATE-REDUCTASE; STRUCTURAL-CHANGE; SPIN RELAXATION; LIGAND-BINDING; SPECTROSCOPY;
Keywords:
GLUCOSE/GALACTOSE RECEPTOR; GGR; F-19 NMR; FLUOROTRYPTOPHAN; PROTEIN DYNAMICS;
Tipo documento:
Article
Natura:
Periodico
Settore Disciplinare:
Science Citation Index Expanded
Science Citation Index Expanded
Citazioni:
40
Recensione:
Indirizzi per estratti:
Citazione:
L.A. Luck et al., "F-19 NMR RELAXATION STUDIES ON 5-FLUOROTRYPTOPHAN-LABELED AND TETRADEUTERO-5-FLUOROTRYPTOPHAN-LABELED ESCHERICHIA-COLI GLUCOSE GALACTOSE RECEPTOR/", Journal of biomolecular NMR, 7(4), 1996, pp. 261-272

Abstract

F-19 NMR relaxation studies have been carried out on a fluorotryptophan-labeled E. coli periplasmic glucose/galactose receptor (GGR). The protein was derived from E. coli grown on a medium containing a 50:50 mixture of 5-fluorotryptophan and [2,4,6,7-H-2(4)]-5-fluorotryprophan. As a result of the large gamma-isotope shift, the two labels give riseto separate resonances, allowing relaxation contributions of the substituted indole protons to be selectively monitored. Spin-lattice relaxation rates were determined at field strengths of 11.75 T and 8.5 T, and the results were analyzed using a model-free formalism. In order toevaluate the contributions of chemical shift anisotropy to the observed relaxation parameters, solid-state NMR studies were performed on [2,4,6,7-H-2(4)]-5-fluorotryptophan. Analysis of the observed F-19 powder pattern lineshape resulted in anisotropy and asymmetry parameters ofDelta sigma = -93.5 ppm and eta = 0.24. Theoretical analyses of the relaxation parameters are consistent with internal motion of the fluorotryptophan residues characterized by order parameters S-2 of similar to 1, and by correlation rimes for internal motion similar to 10(-11) s. Simultaneous least squares fitting of the spin-lattice relaxation and line-width data with tau(i) set al 10 ps yielded a molecular correlation time of 20 ns for the glucose-complexed GCR, and a mean order parameter S-2=0.89 for fluorotryptophan residues 183, 127, 133, and 195. By contrast, the calculated order parameter for FTrp(284), located on the surface of the protein, was 0.77. Significant differences among the spin-lattice relaxation rates of the five fluorotryptophan residues of glucose-complexed GGR were also observed, with the order of relaxation rates given by: R(1F)(183)>R(1F)(127)similar to R(1F)(133)similar to R(1F)(195)>R(1F)(284). Although such differences may reflect motional variations among these residues, the effects are largely predicted by differences in the distribution of nearby hydrogen nuclei, derived from crystal structure data. In the absence of glucose, spin-lattice relaxation rates for fluorotryptophan residues 183, 127, 133, and 195 were found to decrease by a mean of 13%, while the value for residue 284 exhibits an increase of similar magnitude relative to the liganded molecule. These changes are interpreted in terms of a slower overall correlation time for molecular motion, as well as a change in the internal mobility of FTrp(284), located in the hinge region of the receptor.

ASDD Area Sistemi Dipartimentali e Documentali, Università di Bologna, Catalogo delle riviste ed altri periodici
Documento generato il 03/12/20 alle ore 15:41:11