Pyridine hemochromogen

Fig. 4. Visible spectra of catalase, compound I, and compound II 5 [xM (heme) beef liver catalase (Boehringer-Mannheim) in 0.1 M potassium phosphate buffer pH 7.4, 30°C. Compound I was formed by addition of a slight excess of peroxoacetic acid. Compound II was formed from peroxoacetic acid compound I by addition of a small excess of potassium ferrocyanide. Absorbance values are converted to extinction coefficients using 120 mM for the coefficient at 405 nm for the ferric enzyme (confirmed by alkaline pyridine hemochromogen formation). Spectra are corrected to 100% from occupancies of f 90% compound I, 10% ferric enzyme (steady state compound I) and 88% compound II, 12% compound I (steady state compound II). The extinction coefficients for the 500 to 720 nm range have been multiplied by 10. Unpublished experiments (P.N., 1999).

Figure 12. MCD spectra of the pyridine hemochromogens (ferrous bis-pyridine adducts) of alkaline-denatured Spirographis heme-reconstituted myoglobin (-----) and myeloperoxidase (-----) (both in A) and of iron oc-...

Hematin a was prepared from purified cytochrome oxidase as described (29). The hematin solution was made by dissolving the dried samples in phosphate buffer containing 1% Emasol 1130. Its concentration was determined by the pyridine hemochromogen method in a mixture of 20% pyridine and 0.05N NaOH an extinction coefficient of 27.4 mM cm." at 589 m/x was used (29). 

Hemochromes (hemochromogens). Complex compounds of heme with bases such as primary amines, ammonia, pyridine, nicotine, imidazole, etc. when Fe(IIl) is the central atom instead of Fe(ll), the term is hemichromes or ferrihemochromes. 

Hemochromogens are heme compounds with two nitrogen bases, such as pyridine and ammonia, occupying coordination places 5 and 6. The protein moiety is denatured under these conditions. 

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