Studies on Enzyme Action. 



189 



[Note added June 18. — In a communication which came to our notice only 

 when the work we have described was completed Bournot (15) has called 

 attention to the activity of the lipase present in the seeds of Chelidonium majus, 

 the common Celandine, a papaveraceous plant. Having been able, through 

 the courtesy of Messrs. Parke, Davis and Co., to obtain a sample of the seed, 

 we have contrasted its activity with that of our Ricinus lipase and have 

 confirmed Bournot's statement that it is not necessary to treat the seed with' 

 acid to render it active. 



According to Bournot, Chelidonium lipase differs from Ricinus lipase in 

 being most active in a neutral medium, even N/50 acid having an inhibitory 

 effect. But as is shown in Part II, when once liberated from its zymogen 

 Ricinus lipase is also sensitive to acid : in our experience, it has maximum 

 activity when the acidity does not exceed that of oleic acid. 



The enzymes from the two sources both hydrolyse and synthesise glyceric 

 oleate with about the same ease and give rise to mixtures similar in composi- 

 tion at the equilibrium point. But weight for weight, the Tanaka Ricinus 

 preparation is less active than Chelidonium seed (free from oil) in effecting 

 the synthesis of isoprimary butylic oleate. Thus in an experiment in which 

 41 per cent, of the acid was combined by the agency of the Ricinus enzyme, 

 about 80 per cent was etherified by Chelidunium seed. Apparently, the 

 alcohol has a specially marked effect on the Ricinus preparation, as olive oil 

 is hydrolysed only to a small extent in presence of a molecular proportion of 

 isobutylic alcohol to one of the oleate. 



Similarly, on hydrolysing isobutylic oleate, whereas, in presence of a single 

 molecular proportion of water, 9 - 3 per cent, of change was effected in 17 hours 

 by the Chelidonium enzyme, the Ricinus preparation caused only 2 - 4 per 

 cent, of change. The difference was less marked on using 10 times as much 

 water, as 16 - 7 per cent, was hydrolysed by the one and 13 - per cent, by the 

 other " enzyme " : in this case, the effect of the alcohol was reduced apparently 

 by the presence of the excess of water. 



In our opinion, such differences as are observed are to be regarded, 

 provisionally at all events, as consequences of differences in the " condition " 

 of the enzyme in the different seeds. At present, as it is impossible to arrive 

 at any estimate of the " concentration " of an enzyme or to allow for differences 

 in its distribution, we cannot well make any valid comparison of the enzymes 

 of like function derived from different sources.] 



VOL. lxxxviii. — B. 



