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Titolo:
PROTON NMR-SPECTROSCOPY AS A PROBE OF DINUCLEAR COPPER(II) ACTIVE-SITES IN METALLOPROTEINS - CHARACTERIZATION OF THE HYPERACTIVE COPPER(II)-SUBSTITUTED AMINOPEPTIDASE FROM AEROMONAS-PROTEOLYTICA
Autore:
HOLZ RC; BENNETT B; CHEN GJ; MING LJ;
Indirizzi:
UTAH STATE UNIV,DEPT CHEM & BIOCHEM LOGAN UT 84322 UNIV S FLORIDA,DEPT CHEM TAMPA FL 33620 UNIV S FLORIDA,INST BIMOL SCI TAMPA FL 33620
Titolo Testata:
Journal of the American Chemical Society
fascicolo: 25, volume: 120, anno: 1998,
pagine: 6329 - 6335
SICI:
0002-7863(1998)120:25<6329:PNAAPO>2.0.ZU;2-C
Fonte:
ISI
Lingua:
ENG
Soggetto:
NUCLEAR-MAGNETIC-RESONANCE; H-1-NMR SPECTROSCOPY; MOLECULAR-STRUCTURE; COMPLEXES; MODELS; HEMOCYANIN; PROTEINS; SHIFTS; LIGANDS; BINDING;
Tipo documento:
Article
Natura:
Periodico
Settore Disciplinare:
Science Citation Index Expanded
Citazioni:
53
Recensione:
Indirizzi per estratti:
Citazione:
R.C. Holz et al., "PROTON NMR-SPECTROSCOPY AS A PROBE OF DINUCLEAR COPPER(II) ACTIVE-SITES IN METALLOPROTEINS - CHARACTERIZATION OF THE HYPERACTIVE COPPER(II)-SUBSTITUTED AMINOPEPTIDASE FROM AEROMONAS-PROTEOLYTICA", Journal of the American Chemical Society, 120(25), 1998, pp. 6329-6335

Abstract

Proton NMR spectra of the hyperactive Cu(II)-substituted aminopeptidase from Aeromonas proteolytica (AAP) were recorded in both H2O and D2Obuffered solution at pH 6.7. Several remarkably sharp, well resolved hyperfine shifted LH NMR signals were observed in the 70 to -20 ppm chemical shift range. That hyperfine shifted signals were observed is due to spin-coupling of the two Cu(II) ions. Comparison of the spectra recorded in H2O and D2O buffered solutions indicated that the signals at 44.6, 43.3, and 17.7 ppm were solvent exchangeable. The two most strongly downfield shifted signals were assigned to imidazole N-H protonsof the two coordinated histidine residues, while the remaining exchangeable signal was assigned to a peptidyl N-H proton that is in close proximity to the dicopper(II) center. One-dimensional NOE studies at pH6.7 revealed two Y-CH2-CH< moieties that were assigned to coordinatedaspartic acid and histidine residues. In addition, a Y-CH2-CH2-CH< moiety was also identified and was assigned to the coordinated glutamic acid residue, Glu152. All of the hyperfine shifted signals for [CuCu(AAP)] sharpened and shifted toward the diamagnetic region as the temperature was increased following Curie behavior. Fits of these data and those of a series of magnetically diverse mu-phenoxo and mu-alkoxo dicopper(II) model complexes to the population distribution of the ground and first excited states, provided information on the magnetic properties of-dicopper(II) clusters. These fits indicated that the two Cu(II)ions in AAP are ferromagnetically coupled with a 2J value of 50 + 40 cm(-1). These data provide the first structural information regarding the hyperactive [CuCu(AAP)] enzyme and are discussed in terms of the previously proposed mechanism of action for AAP.

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Documento generato il 01/12/20 alle ore 18:49:23