430 IX. HEMATIN ENZYMES, II 



at 640 m/x and increases absorption at 620, 595, and 557 m/x. A pK value 

 of l.S^ for the reaction (Fe^"*") + (F)~ -^ (Fe^"''F) was determined in this 

 way spectrophotometrically. 

 For the reaction: 



(Fe'^^ + OH) + F" -> (Fe*+ F) + OH" 



a pK value of 10.15 was found. The (FeOH) compound is thus half -dissociated 

 at a pH of 3.85, showing that the affinity of lactoperoxidase for hydroxyl (as 

 for fluoride) is greater than that of horse-radish peroxidase. Phosphate of 

 rather high concentrations also combines with the enzyme at pH 5.5. 



The solubility curve of lactoperoxidase in ammonium sulfate solution 

 shows that the enzyme is practically uniform. 



TABLE VII 

 Absorption Spectra of Lactoperoxidase and Its Compounds" 



Absorption maxima"' m;». 

 Compound Color and <niM^'° parentheses) 



Ferriperoxidase Brown-green 640 (low), 600 (7.6), 500 (11.4), 



412 (109), 280 (142) 



Ferroperoxidase Emerald-green [645], 600, 566 



HjOa-compound I Reddish 570, 538 



HoOs-compound II Brownish 617, 594, [540] 



Fe^+CN Yellow-green [595], 560 



Fe'+F Blue-green [620], 590 



Pyridine hemochrome Red 565, 530 



" According to Theorell {2787,2790). 



* Main absorption bands are italicized, weak bands are in brackets. 



Its PZ is rather low (71.5), but pyrogallol may not be a suitable substrate. 

 The activity decreased rapidly and the determination could only be carried 

 out with a lower hydrogen peroxide concentration than usual, and corrected 

 by calculation. 



3.5. Peroxidase of Adrenal Medulla 



In adrenal medulla, Huszak {1377) found a peroxidase, which was particu- 

 larly active against p-phenylenediamine. In reduced form it showed a broad 

 band at 559-553 m/x and a second band at 528 m/x. Carbon monoxide 

 shifted the first band to 570 myu. Cyanide (50% inhibition by 10 M), 

 azide, hydroxylamine, and fluoride inhibited its activity. 



3.6. Peroxidase of Leucocytes 

 (IMyeloperoxidase, "Verdoperoxidase") 



The strong peroxidative activity of pus has long been known. It 

 was observed by Klebs {15I^3) in 1868 and shown by Linossier {1750) 

 in 1898 to be caused by a peroxidase. After fig sap, leucocytes are 



