500 



Dr. E. F. Armstrong. 



[Apr. 5 y 



*[D 7050, 8010; Q 1230.] 



" Studies on Enzyme Action. II. — The Eate of the Change, 

 conditioned by Sucroclasticf Enzymes, and its Bearing on the* 

 Law of Mass Action." By Edward Frankland Armstrong,. 

 Ph.D., Salters' Company's Eesearch Fellow, Chemical Depart- 

 ment City and Guilds of London Institute, Central Technical 

 College. Communicated by Professor H. E. Armstrong,. 

 F.K.S. Eeceived April 5,— Eead April 28, 1904. 



q qqjq j- -Nomenclature or enzymes. 



D 1820 Milk sugar and maltose, hydrolysis by enzymes. 

 D 8010 Emulsin, lactase, maltase — kinetics of their action. 



Although it is now universally recognised that enzymes play a most- 

 important part in animal and plant metabolism and that they even 

 condition synthetic changes, most of the work done has been of a 

 qualitative character ; in only a few cases has the nature of the action 

 been precisely determined — and the results arrived at in these few 

 cases, if not discrepant, cannot easily be harmonised at first sight. 



C. O'Sullivan and Tompsonj were the first to study the action of 

 enzymes quantitatively. They came to the conclusion that the action 

 of invertase on cane sugar takes place in accordance with the ordinary 

 theory of mass action, a theory which involves the assumption that,, 

 throughout an interaction, the amount of change taking place in a 

 given interval of time is always the same proportion of the material 

 remaining unchanged — so that the course of change is expressible by a 

 logarithmic curve. 



Duclaux§ subsequently contended that the rate of change during the 

 early period is directly proportional to the time, although afterwards,, 

 under the influence of the products of hydrolysis, it follows th& 

 logarithmic law. If this suggestion that the action follows the law 



* [Index supplied by communicator, classified according to the schedule of the 

 International Catalogue of Scientific Literature.] 



f [Attention was directed by me in 1890 to the fact that "the terms 

 anxiolytic, proteolytic, etc., are confusing to the student who has learnt that 

 electrolysis signifies splitting up by means of electricity and hydrolysis splitting 

 up by means of water — not the splitting up of electricity or of water." (" The 

 Terminology of Hydrolysis, especially as affected by Ferments," ' Chem. Soc 

 Trans.,' 1890, p. 528.) Unfortunately such terms are still generally used. To avoid 

 the difficulty, I would suggest that enzymes should be spoken of as sucroclastic,. 

 glucosidoclastic, amyloclastic, proteoclastic, lipoclastic, etc., according as they 

 condition the hydrolysis of disaccharides, glucosides, starch, proteids, fats, etc. — 

 H. E. A.] 



X ' Chem. Soc. Trans.,' 1890, vol. 57, p. 843. 

 § ' Ann. Inst. Pasteur,' 1898, vol. 12, p. 96. 



