142 Influence of Low Temperatur es upon Enzymes [March, 



In the course of a study of the influence of temp. on the hydrol- 

 ysis of esters, Hepburn and Pennington (14) demonstrated the 

 activity, in vitro, of the lipase of the crude abdominal fat of the 

 chicken at 0° C. and at — 6.7° to —9.4° C. The increase in acid- 

 ity due to the action of the Hpase for 3 days, in the incubator at 

 40° C, was chosen as a Standard for comparison. With this were 

 compared the increases in acidity, due to the action of the Hpase, for 

 3 days in a house refrigerator (average temp. 17.2° C.) ; for 18 

 days in a mechanically refrigerated chill room at 0° C. ; and for 

 45 days in a mechanically refrigerated freezer at — 6.7° to — 9.4° 

 C The crude fat was extracted with ten-fold its weight of water, 

 and 50 cc. of the extract were permitted to act on i cc. of an 

 ester. The ratios of increase in the acidity of the Substrates were 

 expressed throughout on a basis of the action of the enzyme for a 

 period of 3 days, and the following data were obtained. 



The lipolysis of ethyl acetate in the incubator was twice as rapid 

 as in the refrigerator, 15 times as rapid as in the chill room, and 

 37>4 times as rapid as in the freezer. Ethyl butyrate was hydro- 

 lyzed by lipase in the incubator 2}^ times as fast as in the refriger- 

 ator, 12 times as fast as in the chill room, and 40 times as fast as in 

 the freezer. Ethyl benzoate was split by the enzyme in the incu- 

 bator 8>^ times as rapidly as in the refrigerator, 25^^ times as 

 rapidly as in the chill room, and 255 times as rapidly as in the 

 freezer. The hydrolysis of amyl salicylate by lipase in the incubator 

 was 63/2 times as rapid as in the refrigerator, 13 times as rapid as in 

 the chill room, and 97^^ times as rapid as in the freezer. 



Although the rate of lipolysis was decreased by a lowering of the 

 temp., lipolysis took place even at the temp. of the freezer, while the 

 reaction mixture was frozen solid. 



DiASTASE. Müller (15) prepared a glycerol Solution of dias- 

 tase from the liver of the carp, and used i percent starch paste as 

 Substrate. The volumes of enzyme extract and starch paste were 

 kept constant in the entire series of experiments. The opalescence 

 of the mixture vanished after digestion for i}i min. at 25° C, for 

 5 min. at 8° C, or for 20 min. at 0° C. The Solution then reacted 

 violet to iodin. The Solution first gave a red color with iodin after 

 3M hr. at 25° C, 18 hr. at 8° C, or 32 hr. at 0° C. The Solution 

 lost its power to react with iodin after digestion for 8>^ hr. at 



