Heme proteins:

مرکز و کتابخانه مطالعات اسلامی به زبان های اروپایی

منو

" Heme proteins: "
J. Al-Mustafa J. R. Kincaid

Document Type	:	Latin Dissertation
Language of Document	:	English
Record Number	:	1112892
Doc. No	:	TLpq304140751
Main Entry	:	J. Al-Mustafa
	:	J. R. Kincaid
Title & Author	:	Heme proteins:\ J. Al-MustafaJ. R. Kincaid
College	:	Marquette University
Date	:	1994
student score	:	1994
Degree	:	Ph.D.
Page No	:	177
Abstract	:	Resonance Raman (RR) spectroscopy has been employed to investigate the structure of the cyanide adducts of horseradish peroxidase (HRP) in the pH range 5.5 to 12.5. Evidence for the binding of cyanide in two forms is observed. In the first conformer the usd\nu\lbrackusdFe-CN) stretching mode occurs at higher frequency than the usd\delta\lbrackusdFe-C-N) bending mode, behavior characteristic of an essentially linear Fe-C-N linkage. In the second conformer this ordering is reversed, indicative of a bent Fe-C-N linkage. Furthermore, the axial mode vibrations of the Fe-C-N linkage of both conformers were found to shift upon raising the pH, consistent with deprotonation of a distal histidine. Investigation of cyanide bound beef liver catalase (BLC) and Aspergillus niger catalase (ANC) in the pH range 4.9-11.5 revealed a similar spectral behavior which is also indicative of the presence of linear and bent conformers. The two conformers persist in the pH range 4.9-11.5. At high pH, the usd\nu\lbrackusdFe-CN) mode of the linear conformer of BLC-CN shifts to lower frequency while that of the bent conformer remains unchanged. The propensity for cyanide to bind to these proteins in two conformations and the observed pH dependent shifts are attributable to distal- and proximal-side interactions that modulate the binding geometry of the cyanide ligand. The reactive intermediates of HRP and mesoheme-substituted HRP (meso-HRP) have been investigated by RR spectroscopy. The high frequency RR spectra of HRP compound I reveal a behavior that is consistent with the presence of a usd\piusd-cation radical having an A2u ground state electronic configuration. However, meso-HRP compound I displayed a behavior that is characteristic of an A1u configuration. This alteration in configuration is reasonably attributable to the change in the nature of the heme peripheral substituents. Investigation of the low frequency spectra of meso-HRP compound I revealed an isotope-sensitive mode at 794 cm that has been assigned to the usd\nu\lbrackusdFe=O) stretching vibration.
Subject	:	catalase
	:	Chemistry
	:	horseradish peroxidase
	:	Pure sciences