202 Dr- G- Senter. [June 2, 



of hydrogen peroxide are due to the same substance, and this has 

 teen the generally accepted opinion* until very recently. Schmidt 

 long ago suggested that the catalysis of hydrogen peroxide by blood 

 is due to the haemoglobin, and though this view had been combated 

 by Robert, t Schar,| and others, no very definite evidence had been 

 brought forward on either side. 



Last year the author succeeded in preparing from defibrinated 

 ox blood a body which energetically decomposes hydrogen peroxide 

 and does not give the guaiacum reaction. This body, which has so far 

 been obtained only in solution, has been named hsemase. 



In the former paper] | it has been shown that hsemase rapidly loses 

 its activity when heated in dilute aqueous solution to 60 j that in 

 moderately dilute hydrogen peroxide solutions hsemase undergoes 

 slow oxidation by the peroxide simultaneously with the catalysis of 

 the latter, but that in dilute (ft/100) peroxide solutions the latter is 

 split up without the catalysor being affected. It has also been shown 

 that in dilute solution the velocity of the decomposition of the 

 peroxide is, within fairly wide limits, proportional to the hsemase 

 concentration and to the concentration of the hydrogen peroxide. 

 Preliminary investigation of the effect of other substances on the 

 reaction showed that it is greatly retarded by very small amounts 

 of acids and alkalis and to a much smaller extent by sodium chloride. 



As regards the nature of the catalysor in question there seems good 

 reason to regard it as belonging to that rather indefinite class of 

 substances known as enzymes. In the present state of our knowledge 

 no good definition of an enzyme can be given. We may regard them 

 as substances formed by living cells which can be separated from 

 the latter without losing their activity, and under whose influence 

 certain chemical changes are brought about in a catalytic manner. 

 They are soluble in water, precipitated by alcohol, destroyed by 

 heating in aqueous solution to 60 or 70, and their activity is often 

 greatly influenced by small traces of foreign bodies. In all respects 

 hsemase conforms to the above definition. 



Since hsemase (in aqueous solution at 0) is exceedingly stable and 

 the velocity measurements are so accurately reproducible on different 

 occasions (remarkably so for an enzyme action), the investigation has 

 been continued with the hope of throwing some light on the nature 

 of the enzyme, and the present communication contains an account of 

 the influence of various substances on the rate of reaction. 



* Vide Oppenheimer, ' Ferments,' p. 45. 

 t ' Naturforscherversammlung Aachen,' 1900, quoted by Bredig, ' Anorganische 

 Fermente,' Leipzig, 1901, p. 88. 



I ' Zeit. fur Biologic,' rol. 19, p. 330 (1899). 



' Zeit. fur physik. Chemie,' vol. 44, p. 257 (1903). 



|| Senter, loc. cit. 



