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Can gas replace protein function? CO abrogates the oxidative toxicity of myoglobin.

Sher EA, Sholto AY, Shaklai M, Shaklai N - PLoS ONE (2014)

Bottom Line: The main cause of LDL oxidation by Hb was found to be hemin which readily transfers from Hb to LDL.These reactions were fully arrested by CO.The data are interpreted to suit several circumstances, some physiological, such as high muscle activity, and some pathological, such as rhabdomyolysis, ischemia/reperfusion and skeletal muscle disuse atrophy.

View Article: PubMed Central - PubMed

Affiliation: Department of Human Genetics and Biochemistry, Sackler Faculty of Medicine, Tel Aviv University, Tel Aviv, Israel.

ABSTRACT
Outside their cellular environments, hemoglobin (Hb) and myoglobin (Mb) are known to wreak oxidative damage. Using haptoglobin (Hp) and hemopexin (Hx) the body defends itself against cell-free Hb, yet mechanisms of protection against oxidative harm from Mb are unclear. Mb may be implicated in oxidative damage both within the myocyte and in circulation following rhabdomyolysis. Data from the literature correlate rhabdomyolysis with the induction of Heme Oxygenase-1 (HO-1), suggesting that either the enzyme or its reaction products are involved in oxidative protection. We hypothesized that carbon monoxide (CO), a product, might attenuate Mb damage, especially since CO is a specific ligand for heme iron. Low density lipoprotein (LDL) was chosen as a substrate in circulation and myosin (My) as a myocyte component. Using oxidation targets, LDL and My, the study compared the antioxidant potential of CO in Mb-mediated oxidation with the antioxidant potential of Hp in Hb-mediated oxidation. The main cause of LDL oxidation by Hb was found to be hemin which readily transfers from Hb to LDL. Hp prevented heme transfer by sequestering hemin within the Hp-Hb complex. Hemin barely transferred from Mb to LDL, and oxidation appeared to stem from heme iron redox in the intact Mb. My underwent oxidative crosslinking by Mb both in air and under N2. These reactions were fully arrested by CO. The data are interpreted to suit several circumstances, some physiological, such as high muscle activity, and some pathological, such as rhabdomyolysis, ischemia/reperfusion and skeletal muscle disuse atrophy. It appear that CO from HO-1 attenuates damage by temporarily binding to deoxy-Mb, until free oxygen exchanges with CO to restore the equilibrium.

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Soret absorption spectra of peroxide-activated HRP in anaerobic atmospheres.HRP (3 µM) was mixed with H2O2 (100 µM) and LDL (100 µg protein/ml) at anaerobic conditions provided by either N2 (A) or CO (B). Soret region absorption spectra were recorded at time zero (solid line) and following 60 min (dashed line) of incubation at 37°C. A representative result of 3 independent experiments is shown.
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pone-0104075-g006: Soret absorption spectra of peroxide-activated HRP in anaerobic atmospheres.HRP (3 µM) was mixed with H2O2 (100 µM) and LDL (100 µg protein/ml) at anaerobic conditions provided by either N2 (A) or CO (B). Soret region absorption spectra were recorded at time zero (solid line) and following 60 min (dashed line) of incubation at 37°C. A representative result of 3 independent experiments is shown.

Mentions: Previously, it was reported that HRP was completely unable to peroxidize LDL in the presence of CO [42], but no mechanism was suggested. We showed in the current study that Mb does not release heme easily, operating as an intact enzyme (Fig. 5). In Fig. 6, we show absorption spectra of HRP in the Soret region of reaction mixtures containing CO and peroxide at time zero and after one hour's incubation. Fig. 6A depicts practically no change in the Soret peak of the heme following incubation in nitrogen. In contrast, Fig. 6B demonstrates that under CO, ferric heme was reduced to carboxy-ferrous heme, locking the enzyme in a redox inactive state. This mechanism provides an explanation for the previous observation that LDL oxidation is arrested in the presence of CO [42].


Can gas replace protein function? CO abrogates the oxidative toxicity of myoglobin.

Sher EA, Sholto AY, Shaklai M, Shaklai N - PLoS ONE (2014)

Soret absorption spectra of peroxide-activated HRP in anaerobic atmospheres.HRP (3 µM) was mixed with H2O2 (100 µM) and LDL (100 µg protein/ml) at anaerobic conditions provided by either N2 (A) or CO (B). Soret region absorption spectra were recorded at time zero (solid line) and following 60 min (dashed line) of incubation at 37°C. A representative result of 3 independent experiments is shown.
© Copyright Policy
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4128816&req=5

pone-0104075-g006: Soret absorption spectra of peroxide-activated HRP in anaerobic atmospheres.HRP (3 µM) was mixed with H2O2 (100 µM) and LDL (100 µg protein/ml) at anaerobic conditions provided by either N2 (A) or CO (B). Soret region absorption spectra were recorded at time zero (solid line) and following 60 min (dashed line) of incubation at 37°C. A representative result of 3 independent experiments is shown.
Mentions: Previously, it was reported that HRP was completely unable to peroxidize LDL in the presence of CO [42], but no mechanism was suggested. We showed in the current study that Mb does not release heme easily, operating as an intact enzyme (Fig. 5). In Fig. 6, we show absorption spectra of HRP in the Soret region of reaction mixtures containing CO and peroxide at time zero and after one hour's incubation. Fig. 6A depicts practically no change in the Soret peak of the heme following incubation in nitrogen. In contrast, Fig. 6B demonstrates that under CO, ferric heme was reduced to carboxy-ferrous heme, locking the enzyme in a redox inactive state. This mechanism provides an explanation for the previous observation that LDL oxidation is arrested in the presence of CO [42].

Bottom Line: The main cause of LDL oxidation by Hb was found to be hemin which readily transfers from Hb to LDL.These reactions were fully arrested by CO.The data are interpreted to suit several circumstances, some physiological, such as high muscle activity, and some pathological, such as rhabdomyolysis, ischemia/reperfusion and skeletal muscle disuse atrophy.

View Article: PubMed Central - PubMed

Affiliation: Department of Human Genetics and Biochemistry, Sackler Faculty of Medicine, Tel Aviv University, Tel Aviv, Israel.

ABSTRACT
Outside their cellular environments, hemoglobin (Hb) and myoglobin (Mb) are known to wreak oxidative damage. Using haptoglobin (Hp) and hemopexin (Hx) the body defends itself against cell-free Hb, yet mechanisms of protection against oxidative harm from Mb are unclear. Mb may be implicated in oxidative damage both within the myocyte and in circulation following rhabdomyolysis. Data from the literature correlate rhabdomyolysis with the induction of Heme Oxygenase-1 (HO-1), suggesting that either the enzyme or its reaction products are involved in oxidative protection. We hypothesized that carbon monoxide (CO), a product, might attenuate Mb damage, especially since CO is a specific ligand for heme iron. Low density lipoprotein (LDL) was chosen as a substrate in circulation and myosin (My) as a myocyte component. Using oxidation targets, LDL and My, the study compared the antioxidant potential of CO in Mb-mediated oxidation with the antioxidant potential of Hp in Hb-mediated oxidation. The main cause of LDL oxidation by Hb was found to be hemin which readily transfers from Hb to LDL. Hp prevented heme transfer by sequestering hemin within the Hp-Hb complex. Hemin barely transferred from Mb to LDL, and oxidation appeared to stem from heme iron redox in the intact Mb. My underwent oxidative crosslinking by Mb both in air and under N2. These reactions were fully arrested by CO. The data are interpreted to suit several circumstances, some physiological, such as high muscle activity, and some pathological, such as rhabdomyolysis, ischemia/reperfusion and skeletal muscle disuse atrophy. It appear that CO from HO-1 attenuates damage by temporarily binding to deoxy-Mb, until free oxygen exchanges with CO to restore the equilibrium.

Show MeSH
Related in: MedlinePlus