ANTIBODIES AGAINST RESPIRATORY ENZYMES 393 



present in serum are species specifically different from that derived 

 from Br. abortus, and the immune serum to the latter would be inactive 

 against the normal host phosphatases. 



C. METALLO-PROTEINS AS OXIDATION CATALYSTS AND 



ANTIGENS 



There are a number of oxidative enzymes which contain metals 

 such as Cu, Zn, and Mg. Chlorophyll contains Mg in a manner 

 comparable to iron in heme. Chlorophyll combined with a specific 

 protein constitutes the green pigment of plants. It catalyzes the trans- 

 formation of carbon dioxide into carbohydrate. Zinc is a part of the 

 enzyme carbonic anhydrase which catalyzes the reversible dissociation 

 of carbonic acid. Copper is present in poly-phenol oxidase, known 

 under various names. The question as to whether or not zinc and 

 copper are combined to the protein directly or through prosthetic 

 groups is still unsettled. Of these enzymes, only poly-phenol oxidases 

 have been studied with respect to their antigenic property. 



Gessard (1901, 1902 a, b, c; 1903, 1906) reported that tyrosinase, 

 prepared from the larvae of crustaceans, oxidized tyrosine to a red 

 colored product. The immune sera prepared against tyrosinase and 

 laccase preparations exercised inhibition on the activity of the homolo- 

 gous enzymes. The immune serum against plant tyrosinase did not 

 exercise inhibition on crustacean tyrosinase, but inhibited homologous 

 tyrosinase. Gessard also reported that immune serum against peroxidase 

 from mushrooms, Russula delica, inhibited the activity of homologous 

 peroxidase but had no effect on malt peroxidase.* 



Bach and Engelhardt (1922) repeated the experiments of Gessard 

 and confirmed his findings. Bach and Engelhardt used mushroom 

 extract as laccase. The sera of four rabbits contained potent antibodies, 

 the sera of two rabbits were weak, and the serum of I rabbit was 

 negative. 



^Tyrosinase catalyzes the oxidation of catechol, p-cresol and phenol in the presence 

 of quinone, pyrogallol, dihydroxyphenylalanine, tyramine and adrenalin. Laccase cata- 

 lyzes the oxidation of catechol, guaiacol, p-phenylenediamine in the presence of 

 quinone, pyrogallol, dihydroxyphenylalanine, hydroquinone, vanillin, p-cresol and 

 adrenalin. Peroxidase catalyzes the oxidation of the same substrates catalyzed by 

 laccase; whereas peroxidase uses oxygen from hydrogen peroxide, laccase uses air 

 oxygen (Graubard, 1939). For a critical discussion of the mechanism of the enzy- 

 matic oxidation of phenalic compounds the reader is referred to Nelson and Dawson 

 (1944). 



