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Titolo:
Trans-substitution of the proximal hydrogen bond in myoglobin: I. Structural consequences of hydrogen bond deletion
Autore:
Barrick, D; Dahlquist, FW;
Indirizzi:
Johns Hopkins Univ, TC Jenkins Dept Biophys, Baltimore, MD 21218 USA JohnsHopkins Univ Baltimore MD USA 21218 iophys, Baltimore, MD 21218 USA Univ Oregon, Inst Mol Biol, Eugene, OR 97403 USA Univ Oregon Eugene OR USA 97403 egon, Inst Mol Biol, Eugene, OR 97403 USA
Titolo Testata:
PROTEINS-STRUCTURE FUNCTION AND GENETICS
fascicolo: 4, volume: 39, anno: 2000,
pagine: 278 - 290
SICI:
0887-3585(20000601)39:4<278:TOTPHB>2.0.ZU;2-8
Fonte:
ISI
Lingua:
ENG
Soggetto:
FERROUS-PORPHYRIN COMPLEXES; NUCLEAR MAGNETIC-RESONANCE; CARBON-MONOXIDE; ACTIVE-SITE; SPERM WHALE; HEMOGLOBIN; MODEL; HISTIDINE; DEOXYMYOGLOBIN; HEMOPROTEINS;
Keywords:
hydrogen bonding; protein structure; paramagnetic NMR; chemical rescue; myoglobin;
Tipo documento:
Article
Natura:
Periodico
Settore Disciplinare:
Life Sciences
Citazioni:
36
Recensione:
Indirizzi per estratti:
Indirizzo: Barrick, D Johns Hopkins Univ, TC Jenkins Dept Biophys, 3400 N Charles St,Baltimore,MD 21218 USA Johns Hopkins Univ 3400 N Charles St Baltimore MD USA 21218 USA
Citazione:
D. Barrick e F.W. Dahlquist, "Trans-substitution of the proximal hydrogen bond in myoglobin: I. Structural consequences of hydrogen bond deletion", PROTEINS, 39(4), 2000, pp. 278-290

Abstract

The structural role of a sidechain to side-chain protein hydrogen bond is examined using trans-substitution of the proximal histidine of myoglobin with methylimidazoles (Barrick, Biochemistry 1994;33:6546-6554), Modificationof the chemical structure of exogenous ligands allows this hydrogen bond to be disrupted. Comparison of the crystal structures of H93G myoglobin complexed 4-methylimidazole (4meimd; methylation at carbon 4) and 1-methylimidazole (1meimd; methylation at the adjacent nitrogen, preventing hydrogen bonding between the imidazole ligand and the protein) shows that the polypeptide, heme, and methylimidazole orientations are the same within error. For 4meimd there appear to be major and minor conformations corresponding to different tautomeric states of the ligand, Conformational heterogeneity is also seen in the hyperfine-shifted region of the NMR spectrum of 4meimd complexed with high-spin H93G deoxyMb. The major conformation of the 4meimd ligand and the 1meimd ligand, as seen in the respective crystal structures, are quite similar except that the proximal ligand NH-to-Ser92-OH hydrogen bond is eliminated in the 1meimd complex, and instead the proximal ligand CH is adjacent to the Ser92-OH. Thus, this system provides a means to eliminate the Mb proximal hydrogen bond in a chemically and structurally conservative way. (C) 2000 Wiley-Liss, Inc.

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Documento generato il 14/07/20 alle ore 09:46:30