Peroxidase complex II and

Andersons, B., and J. Gravitis. 1984. Steric and electronic effects on interaction of model substance of the structural unit of hgnin with a peroxidase complex II. Khimaya Drev. 1984(5) 102-103. 

A good correlation of the hydrogen peroxide and peroxidase complex II kinetics is readily obtained with the platinum microelectrode and a sensi-... 

Fig. 8A. A correlation of the appearance and disappearance of peroxidase complex II at 390 mM obtained spectrophotometrically in a rapid flow apparatus and the simultaneous utilization of HtOt (polarographic traces) (Expt. 103).

Fig. 8B. The spectrophotometric recording of the kinetics of peroxidase complex II at 390 m/i and the disappearance of donor (ascorbic acid) at 268 mft. 0.37 iiM horseradish peroxidase, 1.1 nM HtCh, 17 itM ascorbic acid, 0.01 M acetate buffer, pH 4.6 (Expt. 409b).

Fig. 8C. The disappearance of leucomalachite green and the kinetics of peroxidase complex II in a mirror oscillograph recording of the rapid flow technique. Time markers are 0.2 second, pH 4.0 (7) (MC-10).

Gosh, A., J. Almlof, and L. Que Jr. 1994. Density Functional Theoretical Study of Oxo(porphyroinato)iron(IV) Complexes, Models of Peroxidase Compounds I and II. J. Phys. Chem. 98, 5576. 

Another physiological substrate for peroxidases is peroxynitrite. Floris et al. [250] have shown that peroxynitrite rapidly reacts with HRP and MPO, forming Compound II without the intermediate generation of Compound I. These authors proposed that the intermediate complex Compound I N02 immediately decomposed to Compound II and N02 (Reaction (28)). 

The enzyme horseradish peroxidase is a hemoprotein and the region of the Soret band exhibits large differences between the position and extinction coefficients of the uncombined and combined forms. Both forms were first studied by spectrophotometry, but the E—S complexes were 0 labile that they could not be examined extensively by any other spectroscopic method. Using rapid-scanning spectrophotometry and rapid mixing, Chance was able to distinguish the spectra of compound I and II and determine the various rate constants of the multistep reaction with rather poor precision. 

Since compound II has a Soret peak at 420 nm and the oxycomplex 416 nm, the equilibrated solution of compound II, H2O2, and compound III should exhibit an intermediate absorption peak. The existence of such an equilibrium has been established with HRP (22) and was also observed with lignin peroxidase (Cai, D., and Tien, M., unpublished results 23). Wariishi and Gold (25) recently proposed the existence of a new enzyme intermediate when compound in is formed in the presence of H2O2. They referred to this intermediate as compound III and suggested it to be a complex between compound III and H2O2. The existence of such an intermediate was based primarily on the Soret spectral properties where a 419 nm maximum was observed. In contrast, we see no evidence for existence of such a complex. The observed 419 nm absorbance maximun can be best explained by the existence of both compounds II and III in solution. 

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