Reactions of Haematins and Haemoproteins
نویسنده
چکیده
1. It is shown that free haematins will react with nitric oxide under certain conditions giving compounds with characteristic absorption spectra. 2. The reactions of nitric oxide with both protohaematin and urohaematin were examined. In acid solution each of these haematins changes colour from reddish brown to a bright red in the presence of nitric oxide, and two strong absorption bands appear in the green region ofthe spectrum while the Soret band of the haematin is shifted to a longer wavelength. 3. Urohaematin in alkaline solution reacts similarly with nitric oxide and can be reduced to give a NO-urohaem compound with a single broad absorption band in the visible region. The results obtained with alkaline protohaematin are less clear-cut. 4. The absorption spectra of the NO-compounds ofprotoanduro-haematin under various conditions have been determined. 5. No spectroscopic evidence was obtained for any reaction between fluoride, azide or sulphide with free haematins, although these substances all form well-defined compounds with methaemoglobin and other haemoproteins. 6. The reactions of different substances with free iron-porphyrins were compared with those given with haemoproteins. Of all the substances examined only nitric oxide and the cyanide ion are capable of co-ordinating with the bivalent and tervalent iron of haem and haematin respectively, both when they are free and when they form the prosthetic groups of haemoproteins.
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تاریخ انتشار 2005