Enzymes 173 



is some overlapping between individual enzymes and groups 

 of enzymes; thus alkaline phosphomonoesterase will hydro- 

 lyze nucleic acids quite readily, although most of the phos- 

 phate is in diesteric linkage; some pyrophosphatases will at- 

 tack adenosinetriphosphate. 



Table 2 is essentially the classification of Folley and Kay,* 

 expanded somewhat to include more recent data. It contains 

 most but not all of the dephosphorylating enzymes whose 

 specificities are reasonably well established. For more de- 

 tailed information, the reader is referred to textbooks of 

 enzymology.^ 



Of the large variety of phosphatases, histochemical meth- 

 ods are available for nonspecific alkaline phosphatase, for 5- 

 nucleotidase, acid phosphatase, and phosphamidase. A few 

 data have been published on pyrophosphatase^' ^ and meta- 

 phosphatase.^' '^ Glick and Fischer^ reported the histochemi- 

 cal localization of adenosinetriphosphatase in plant and ani- 

 mal tissue; but the specificity of their results has been ques- 

 tioned.^ Soulairac and Desclaux^^ obtained positive results 

 for adenosinetriphosphatase in rat muscle. Landschiitz^^ 

 found that adenosinetriphosphatase can be demonstrated in 

 the cells of the Ehrlich mouse carcinoma. 



No histochemical methods have been devised for the re- 

 mainder of the group. Some of the phosphatases are so sen- 

 sitive that they will not tolerate fixation and/or embedding 

 (hexosediphosphatase, adenosinetriphosphatase of muscle). 



4. Folley, S. J., and Kay, H. D.: Ergebn. d. Enzymforsch., 5:159, 1936. 



5. Albers, H.: Phosphatasen. In Nord and Weidenhagen's Handb. d. 

 Enzymologie (Leipzig: Akad. Verlagsgesellschaft., 1940), 1:408; Roche, 

 J.: Phosphatases. In Sumner and Myrback^s The enzymes (New York: Aca- 

 demic Press, 1950), I, 1:473. 



6. Nickerson, W. J., Krugelis, E. J., and Andresen, N.: Nature, 162:192, 

 1948. 



7. Gomori, G.: Proc. Soc. Exper. Biol. & Med., 70:7, 1949. 



8. GHck, D., and Fischer, E. E.: Science, 102:429, 1945. 



9. Moog, F., and Steinbach, H. B.: Science, 103:144, 1946. 



10. Soulairac, A., and Desclaux, P.: Compt. rend. Soc. de biol,, 143:470, 

 1949. 



11. Landschiitz, C.: Experientia, 6:232, 1950. 



