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Titolo:
Mapping the pathways for O-2 entry into and exit from myoglobin
Autore:
Scott, EE; Gibson, QH; Olson, JS;
Indirizzi:
Rice Univ, Dept Biochem & Cell Biol, Houston, TX 77005 USA Rice Univ Houston TX USA 77005 Biochem & Cell Biol, Houston, TX 77005 USA Rice Univ, WM Keck Ctr Computat Biol, Houston, TX 77005 USA Rice Univ Houston TX USA 77005 k Ctr Computat Biol, Houston, TX 77005 USA
Titolo Testata:
JOURNAL OF BIOLOGICAL CHEMISTRY
fascicolo: 7, volume: 276, anno: 2001,
pagine: 5177 - 5188
SICI:
0021-9258(20010216)276:7<5177:MTPFOE>2.0.ZU;2-3
Fonte:
ISI
Lingua:
ENG
Soggetto:
SPERM WHALE MYOGLOBIN; SITE-DIRECTED MUTAGENESIS; LIGAND-BINDING; MOLECULAR-DYNAMICS; CRYSTAL-STRUCTURES; PROTEIN DYNAMICS; DISTAL HISTIDINE; CARBON-MONOXIDE; HEME-PROTEINS; XENON COMPLEX;
Tipo documento:
Article
Natura:
Periodico
Settore Disciplinare:
Life Sciences
Citazioni:
58
Recensione:
Indirizzi per estratti:
Indirizzo: Olson, JS Rice Univ, Dept Biochem & Cell Biol, MS 140,6100 Main St, Houston, TX 77005 USA Rice Univ MS 140,6100 Main St Houston TX USA 77005 TX 77005 USA
Citazione:
E.E. Scott et al., "Mapping the pathways for O-2 entry into and exit from myoglobin", J BIOL CHEM, 276(7), 2001, pp. 5177-5188

Abstract

The effects of mutagenesis on geminate and bimolecular O-2 rebinding to 90mutants at 27 different positions were used to map pathways for ligand movement into and out of sperm whale myoglobin. By analogy to a baseball glove, the protein "catches" and then "holds" incoming ligand molecules long enough to allow bond formation with the iron atom. Opening of the glove occursby outward movements of the distal histidine (His(64)), and the ligands are trapped in the interior "webbing" of the distal pocket, in the space surrounded by Ile(28), Leu(29), Leu(32), Val(68), and Ile(107). The size of this pocket is a major determinant of the rate of ligand entry into the protein. Immediately after photo- or thermal dissociation, O-2 moves away from the iron into this interior pocket. The majority of the dissociated ligands return to the active site and either rebind to the iron atom or escape through the His(64) gate. A fraction of the ligands migrate further away from the heme group into cavities that have been defined as Xe binding sites 4 and1; however, most of these ligands also return to the distal pocket, and net escape through the interior of wildtype myoglobin is <20-25%.

ASDD Area Sistemi Dipartimentali e Documentali, Università di Bologna, Catalogo delle riviste ed altri periodici
Documento generato il 01/12/20 alle ore 22:13:02