The pH dependence of the kinetics of the binding of cyanide ion to methemoglobins A and S and to guinea pig and pigeon methemoglobins appears to be not directly correlated with the net charges on the proteins. The kinetics can, however, be adequately explained in terms of three sets of heme-linked ionizable groups with pK1 ranging between 4.9 and 5.3, pK2 between 6.2 and 7.9, and pK3 between 8....

Band assignment for oxy, deoxy and methemoglobin using orbital promotion is crucial to understanding inter-relation of electronic transitions. Spectral changes may be correlated with conformational alteratiions. Conformational changes of hemoglobin were interpreted using four-orbital model of Gouterman. Our results indicated that Goutherman model can predict the predominant conformations of hem...

S OF SPECIAL INTEREST THE RESTORATION OF METHEMOGLOBIN BY MEANS OF GLUTAMIC ACID. A. Al. Genkin and M. C. Volkov. From the Sverdlovsk Medical Institute. Bulletin of Experimental Biology and Medicine, USSR. 47:50, 1959. A lethal dose of sodium nitrite was injected into rats. All died. The average methemoglobin content of blood collected just before death was 72 per cent. Another group of rats re...

Methemoglobin mav be formed from hemoglobin in vitro bv a wide range of oxidizing agents. Such compounds also act in vivo if they ian permeate the red cell membrane; other substances such as aniline and &its derivatives (including the sulfanilimide series) are ineffective with hemoglobin solutions but do form methemoglobin in vivo, possibly because they give rise, in the course of their metabol...

A simple, reliable and rapid method for the spectrophotometric determina­ tion of carboxyhemoglobin in fresh blood is described. A blood hemolysate is prepared by diluting a blood sample with 0.4 percent NH4 OH. Addition of sodium dithionite deoxygenates hemoglobin (and reduces methemoglobin if present) without affecting carboxyhemoglobin. Comparison of the 541/555 nm absorbance ratio for the h...

Erythrocytic NADH methemoglobin diaphorase acquires NADH-dichlorophenolindophenol diaphorase activity when enzyme-associated NAD is removed. This transformation is reversible and can be mediated by membrane NAD glycohydrolase (EC 3.2.2.5) in hemolysates as well as in intact cells exposed to hydrogen peroxide. It is abolished either in NADH methemoglobin diaphorase deficiency or in NAD(P) glycoh...

Protective effects of metallothionein (MT) have been studied against dimethylnitosamine (DMN) toxicity in laboratory rats. MT was induced by feeding rats on repeated sublethal doses of cadmium and zinc. These rats were subsequently administered DMN. Methemoglobin and nitric oxides, the established markers of DMN toxicity, were estimated in the blood samples of MT protected rats. Preinduction of...