118 LIFE: ITS NATURE AND ORIGIN 



Peroxidase forms two highly unstable compounds with H 2 2 , whose 

 decomposition is much accelerated by the acceptor present in plant 

 extract or by the addition of other acceptors, e.g., ascorbic acid, 

 hydroquinone, or pyrogallol. "The same hematin nucleus combined 

 with three different native proteins forms three distinct compounds: 

 methemoglobin, catalase, and peroxidase, which have many properties 

 in common but show, however, striking differences in the nature and 

 magnitude of their catalytic activities." Warburg and Christian 41 

 report that the old "yellow enzyme" may really be an artifact resulting 

 from the loss of adenylic acid during its preparation. They describe 

 five different yellow enzymes, some with similar proteins but different 

 prosthetic groups, others with the same prosthetic group but different 

 proteins. The protein/prosthetic group combination is reversible, 

 and it is estimated that one molecule of alloxine dinucleotide can 

 transfer 1440 molecules of oxygen per minute. Vegetables and fruits 

 are "blanched" by steam before being dehydrated, to inactivate 

 enzymes which cause undesirable changes. 



This gives us some insight as to the potency and flexibility of the 

 enzymic catalyst systems of living cells, and effectively answers the 

 antiquated gibe of orthodox organic chemists that whenever a biolog- 

 ical reaction is to be explained, a new enzyme is invented. 



The formation of chlorophyll seems to demand the presence of iron, 

 just as the formation of erythrocytes in man demands the presence of 

 copper. The mode of formation of prosthetic groups is generally 

 obscure, 42 but it has recently been shown that thiamin (vitamin B x ) is 

 combined with pyrophosphoric acid, 43 and D. E. Green states: 42 

 "There is ample evidence of the existence in animal tissues and micro- 

 organisms of enzymes which catalyze the phosphorylation of thiamin 

 as well as the dephosphorylation of diphosphothiamin." Some ani- 

 mals (man) must eat vitamin C; others (rats) can synthesize it, or in 

 any event do without it in their food. 



Nature, with infinite time and opportunity for experiment, accom- 

 plishes results in manifold and devious ways. Thus the ascidian 

 Phallusia mamillata has an acid blood (3 per cent H 2 S0 4 ) which con- 

 tains as chromogen a non-dialysable organo-vanadium compound. 

 On plasmolysis this gives a brown solution, which yields, on drying, a 

 dark-blue powder showing over 10 per cent vanadium (two analyses 

 gave 10.36 and 15.4 per cent, but the latter figure is doubtful). Mus- 

 sels have a manganese-containing catalyst, pinnaglobin. Most crus- 

 taceans, including Limulus (the horse-shoe or king crab, of antediluvian 

 ancestry) are literally blue-blooded because of copper-containing 

 hemocyanin. A group of African birds known as the Touracous or 

 Plantain-eaters have in their pinion feathers red or crimson patches 

 or portions from which weak alkali or soap solutions will extract a 

 pigment, which, after precipitation by acid, dries to a rich crimson 



