Lack of allosterically controlled intramolecular transfer of nitric oxide from the heme to cysteine in the subunit of hemoglobin
نویسندگان
چکیده
The SNO-Hb hypothesis holds that hemebound nitric oxide (NO) present in the subunits of T-state hemoglobin (Hb) will be transferred to the -93 cysteine upon conversion to R-state Hb, thereby forming SNO-Hb. A deficiency in the ability of Hb to facilitate this intramolecular transfer has recently been purported to play a role in pulmonary hypertension and sickle cell disease. We prepared deoxygenated Hb samples with small amounts of hemebound NO and then oxygenated the samples. Electron paramagnetic resonance (EPR) spectroscopy was used to (1) determine the concentration of iron nitrosyl Hb (Fe-NO Hb), (2) show that the NO is evenly distributed among and subunits, and (3) show that the Hb undergoes a change in its quaternary state (T to R) upon oxygenation. We did not observe a decrease in the concentration of Fe-NO Hb on oxygenation, which is inconsistent with the prediction of the SNO-Hb hypothesis. (Blood. 2006;107:2602-2604)
منابع مشابه
Lack of allosterically controlled intramolecular transfer of nitric oxide from the heme to cysteine in the beta subunit of hemoglobin.
The SNO-Hb hypothesis holds that heme-bound nitric oxide (NO) present in the beta subunits of T-state hemoglobin (Hb) will be transferred to the beta-93 cysteine upon conversion to R-state Hb, thereby forming SNO-Hb. A deficiency in the ability of Hb to facilitate this intramolecular transfer has recently been purported to play a role in pulmonary hypertension and sickle cell disease. We prepar...
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