58 



SUBCELLULAR PARTICLES 



2.5 mg DNA 



1.5 mg DNA 



01 mMoles Fe+ + "'' 



15 30 45 60 



Fig. 12. Effect of deoxyribonucleic acid on Fc (III) -catalyzed pyrogallol oxidation. 



and DNA, but it is difficult to select the interaction of greatest influence on the 

 rate of oxidation from among hydrogen bonding of pyrogallol to macromolecule, 

 complexing of iron with macromolecule, and complexing of iron with pyrogallol. 

 Although the problem may be treated in part as one involving the behavior of 

 concentrating surfaces — increased probability that the necessary collisions will 

 occur between reactants — qualitative differences among products and variation 

 in activity among the macromolecules tested suggest the operation of other factors, 

 possibly surface structure and geometry as well. Just as the catalytic effectiveness 

 of heme is enhanced and specificity conferred by conjugation with the appropriate 

 protein moiety to form a particular hemoprotein enzyme, so there is suggested 

 here an analogous system, with Fe(III) replacing heme and non-protein macro- 

 molecules serving in place of the appropriate enzyme protein, or even serving in 

 a dual role, replacing both porphyrin and protein. In addition to their significance 

 as models reflecting diversity among hemoproteins, the cellulose and DNA sys- 

 tems open the possibility that many more catalytically active associations exist in 

 cells than are encompassed in the formal recognition of enzymes, including those 

 containing an immobile member, hence effecting a localization of the catalytic 

 process involved. 



Inorganic Catalysis and Stereospecificity. Pursuing the problem of phenol oxida- 

 tion catalysts has entailed the use of some 70 inorganic substances, including 

 29 elements, 8 metal oxides, and 34 simple salts. The elements tested for their 

 effect on the autoxidation of pyrogallol — Al, Sb, As, B, Cd, C, Cr, Co, Cu, Ga, 

 Au, I, Fe, Pb, Mg, Mn, Hg, Ni, Nb, Pd, Se, Si, Ag, S, Ta, Te, Sn, Zn and W— 

 cover a wide range with respect to physical and chemical properties (36). With 

 comparatively small surface areas, 20—30 cm-, some of these elements affected 

 autoxidation of pyrogallol profoundly. Manganese and cobalt were most effective 

 in accelerating oxidation, with iron and copper next in stimulatory activity; 



