A REVIEW OF RECENT WORK ON 

 ENZYME ACTION 



By R. J. S. McDOWALL, M.B. 



Introductory. — When reviewing the work recently done on 

 enzyme action, nothing perhaps strikes one more forcibly than 

 the farsightedness of Berzelius, who in 1837, when drawing 

 the attention of chemists to enzyme action, recognised that the 

 process was essentially catalytic in nature, and asserted that 

 " in living plants and animals there take place thousands of 

 catalytic processes between tissues and fluids." Since that 

 time three generations of investigators have studied the subject, 

 only to find how true the words of Berzelius were, although in 

 the light of our present knowledge of the factors involved it is 

 difficult to imagine that the author fully realised the significance 

 of them. 



Much of the advance in our knowledge of enzyme action 

 has been made side by side with and is almost consequent on 

 the great advances in our knowledge of inorganic catalysts, 

 surface action and colloids ; it is not, however, within the scope 

 of this essay to deal with these subjects except as regards their 

 bearing on the question under consideration. 



Definition. — A short detailed definition is so difficult to 

 obtain that the more general one of Euler is possibly the best. 

 The following is from the English translation of Euler's General 

 Chemistry of the Enzymes : 



" The name enzyme is given to animal or vegetable sub- 

 stances which are able to accelerate chemical reactions. The 

 term enzyme is included in the general term catalyst. By 

 catalyst we understand a substance which, without being 

 injured by the acceleration or appearing in the final products, 

 alters the velocity with which a chemical system strives to attain 

 its final condition." 



Practically all enzymes are colloids, or are associated with 

 substances having colloidal properties, and in a large number 

 of cases they are found together with protein matter. Thus 

 the amylase obtained by Sherman (191 2-1 7), protease and 



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