These tools will no longer be maintained as of December 31, 2024. Archived website can be found here. PubMed4Hh GitHub repository can be found here. Contact NLM Customer Service if you have questions.


Pubmed for Handhelds

PUBMED FOR HANDHELDS

Search MEDLINE/PubMed

  • Title: Reduction of ferrylmyoglobin and ferrylhemoglobin by nitric oxide: a protective mechanism against ferryl hemoprotein-induced oxidations.
    Author: Gorbunov NV, Osipov AN, Day BW, Zayas-Rivera B, Kagan VE, Elsayed NM.
    Journal: Biochemistry; 1995 May 23; 34(20):6689-99. PubMed ID: 7756300.
    Abstract:
    The reactions of metmyoglobin (metMb) and methemoglobin (metHb), oxidized to their respective oxoferryl free radical species (.Mb-FeIV = O/.Hb-4FeIV = O) by tert-butyl hydroperoxide (t-BuOOH), with nitric oxide (NO.) were studied by a combination of optical, electron spin resonance (ESR), ionspray mass (MS), fluorescence, and chemiluminescence spectrometries to gain insight into the mechanism by which NO. protects against oxidative injury produced by .Mb-FeIV = O/.Hb-4FeIV = O. Oxidation of metMb/metHb by t-BuOOH in a nitrogen atmosphere proceeded via the formation of two protein electrophilic centers, which were heme oxoferryl and the apoprotein radical centered at tyrosine (for the .Mb-FeIV = O form, the g value was calculated to be 2.0057), and was accompanied by the formation of t-BuOOH-derived tert-butyl(per)oxyl radicals. We hypothesized that NO. may reduce both oxoferryl and apoprotein free radical electrophilic centers of .Mb-FeIV = O/.Hb-4FeIV = O and eliminate tert-butyl(per)oxyl radicals, thus protecting against oxidative damage. We found that NO. reduced .Mb-FeIV = O/.Hb-4FeIV = O to their respective ferric (met) forms and prevented the following: (i) oxidation of cis-parinaric acid (PnA) in liposomes, (ii) oxidation of luminol, and (iii) formation of the tert-butyl(per)oxyl adduct with the spin trap DMPO. NO. eliminated the signals of tyrosyl radical detected by ESR and oxoferryl detected by MS in the reaction of t-BuOOH with metMb. As evidenced by MS of apomyoglobin, this effect was due to the two-electron reduction of .Mb-FeIV = O by NO. at the oxoferryl center rather than to nitrosylation of the tyrosine residues. Results of our in vitro experiments suggest that NO. exhibits a potent, targetable antioxidant effect against oxidative damage produced by oxoferryl Mb/Hb.
    [Abstract] [Full Text] [Related] [New Search]