ACTION OF THE ENZYMES. 115 



subsequently redissolved in water. PEKELHARING 1 claims to 

 have prepared the purest acid -pro tei.nase thus far obtained 

 and classes the enzyme among the proteins. His prepara- 

 tion gives the well-known reactions for proteins, and on 

 quantitative analysis shows the presence of carbon, nitrogen, 

 hydrogen, and sulphur in the proportions in which they 

 exist in these bodies. As the preparation contains no phos- 

 phorus it is not considered a nucleo-proteid. In harmony 

 with the findings of NENCKI and SIEBER, PEKELHARING looks 

 upon chlorine as a constant constituent of acid -pro teinase. 

 Should it be shown ultimately that PEKELHARING'S enzyme is 

 not a pure substance it will still have to be looked upon as 

 the most active preparation of this ferment obtained thus far. 

 0.001 milligram in 6 c.c. of a 0.2 percent hydrochloric acid 

 solution dissolved a flake of fibrin in a few hours. 



The acid-proteinase of PEKELHARING is able not only to act 

 on proteins but also curdles milk. This means that acid- 

 proteinase and caseinase are probably parts of the same 

 molecule. As stated above, gastric juice contains a fat-split- 

 ting ferment lipase but the pepsin preparation of PEKEL- 

 HARING shows no fat-splitting activity. This author's work, 

 therefore, supports a view which has been suggested by 

 NENCKI and SIEBER before him, that acid-proteinase and 

 caseinase represent different parts of a giant molecule. 



BRUNTON, 2 and FRIEDENTHAL and MIYAMOTA S have ex- 

 pressed themselves as opposed to the conception of the protein 

 character of pure acid-proteinase and bring forward as proof 

 that they have succeeded in obtaining active acid-proteinase 

 preparations which do not give any of the reactions for pro- 

 teins. It is also pointed out by these authors that acid-pro- 

 fceinase is not digested by alkali-proteinase (trypsin), which as 



1 PEKELHARING: Zeitschrift fiir physio logische Chemie, 1902, XXXV, 

 p. 8. 



2 BRUNTON. Centralblatt fur Physiologic, 1902, XVI, p. 201. 



3 FRIEDENTHAL and MIYAMOTA: Centralblatt fur Physiologic 1901, 

 XV, p, 786; ibid., 1902, XVI, p. 1, 



