Oxyhemoglobin autoxidation

R. Wever, B. Oudega, and B.F. van Gelder, Generation of superoxide radicals during the autoxidation of mammalian oxyhemoglobin. Biochim. Biophys. Acta. 302, 475-478 (1973). 

The reactivity of NO with O2 is dramatically affected upon coordination of one of the diatomic components to a metal center. For example, the second-order reactions of NO with oxyhemoglobin, Hb(02) and oxymyoglobin, Mb(02) (e.g. Eq. (47)) are quite fast and have been used as colorimetric tests for NO (105). The nitrogen product is NO3 rather than N02 that is the product of aqueous autoxidation (106). While the reaction of 02 with nitrosyl myoglobin Mb(NO) (Eq. (48)) might superficially appear similar it is much slower and follows a different rate law (107). Possible mechanisms will be discussed below. 

The autoxidation of oxyhemoglobin, like that of oxymyoglobin, produces OJ (See Sect. 3.2) ... 

Nagababu E, Rifkind JM (2000) Heme degradation during autoxidation of oxyhemoglobin. Biochem Biophys Res Commun 273 839-845... 

The changes of acid-base properties of the globin moiety and their physiological meaning are well-known and will not be discussed here. We would like to draw attention rather to the fact that, in contrast to simple hematin compounds, the Fe++-0.2 complex in oxyhemoglobin is very stable and will but slowly autoxidize. Oxygen restricts electron... 

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