Document Detail

The active form of the ferric heme in neutrophil cytochrome b(558) is low-spin in the reconstituted cell-free system in the presence of amphophil.
MedLine Citation:
PMID:  10502679     Owner:  NLM     Status:  MEDLINE    
The spin state of the heme in superoxide (O(2)(.)(-))-producing cytochrome b(558) purified from pig neutrophils was examined by means of room-temperature magnetic circular dichroism (MCD) under physiological conditions. Cytochrome b(558) with varying amounts of low-spin and high-spin heme was prepared by either pH adjustment or heat treatment, and the O(2)(.)(-)-forming activity in a cell-free system was found to correlate with the low-spin heme content. The possibility that the O(2)(.)(-)-forming activity results from a transient high-spin ferric heme form that is induced during activation by anionic amphophils has also been investigated. EPR spectra of cytochrome b(558) activated by either arachidonic acid or myristic acid, showed that a transient high-spin ferric species accounting for approximately 50% of the heme appeared in the presence of arachidonic acid, but not in the presence of myristic acid. Hence the appearance of a transient high-spin ferric heme species on activation with an amphophil does not afford a common activation mechanism in the NADPH oxidase system. The EPR results for cytochrome b(558) activated with arachidonic acid showed that the transient high-spin ferric heme can bind cyanide. However, the high-spin ferric heme does not contribute to the O(2)(.)(-) production of cytochrome b(558) in cell-free assays in the presence of cyanide.
H Fujii; M G Finnegan; M K Johnson
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Publication Detail:
Type:  In Vitro; Journal Article; Research Support, Non-U.S. Gov't    
Journal Detail:
Title:  Journal of biochemistry     Volume:  126     ISSN:  0021-924X     ISO Abbreviation:  J. Biochem.     Publication Date:  1999 Oct 
Date Detail:
Created Date:  1999-12-30     Completed Date:  1999-12-30     Revised Date:  2007-12-19    
Medline Journal Info:
Nlm Unique ID:  0376600     Medline TA:  J Biochem     Country:  JAPAN    
Other Details:
Languages:  eng     Pagination:  708-14     Citation Subset:  IM    
Department of Inflammation Research, The Tokyo Metropolitan Institute of Medical Science (Rinshoken), Bunkyo-ku, Tokyo, 113-8613, Japan.
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MeSH Terms
Arachidonic Acid / pharmacology
Cell-Free System
Circular Dichroism
Cyanides / pharmacology
Cytochrome b Group / chemistry*,  metabolism
Electron Spin Resonance Spectroscopy
Heme / chemistry*
Myristic Acid / pharmacology
NADPH Oxidase*
Neutrophils / chemistry
Superoxides / metabolism
Reg. No./Substance:
0/Cyanides; 0/Cytochrome b Group; 11062-77-4/Superoxides; 14875-96-8/Heme; 506-32-1/Arachidonic Acid; 544-63-8/Myristic Acid; 9064-78-2/cytochrome b558; EC Oxidase

From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine

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