96 PRELIMINARY COLD STORAGE STUDIES. 



the production of rancidity is still a mooted question. Since bacteria 

 will not propagate in pure, dry fat. but must have present suitable 

 nitrogenous foodstuffs as well as moisture, the conditions for their 

 activity, as pointed out by Lewkowitsch, are the same as for the 

 activity of enzymes, hence it is exceedingly difficult to say where the 

 action of either the one or the other ceases, but it would seem proba- 

 ble that fat splitting can be ascribed to both enzymes and bacteria, 

 whereas the decomposition of the free fatty acids or of the glycerol 

 must be referred to bacteria alone. 



The researches of Kastle and Loevenhart on lipase have established 

 the wide distribution of the enzyme in nature and its stability as well 

 as its adaptability to its environment. It was kept dry and moist, 

 and at room temperatures and in cold storage, retaining its activity 

 for months. It hydrolases most rapidly at 40° C, at which tempera- 

 tare 11.29 per cent of fat splitting was noted; at 10° C. the amount 

 was 3.S9 per cent; at 0° C, 2.26 per cent, and at —10° C, 0.70 

 per cent, a quantity which, given weeks and months in which to aug- 

 ment, might easily reach notable proportions. The enzyme lipase 

 shows a decided preference for fats of higher molecular weight, 

 wherein it differs from the usual acids used to induce hydrolysis. It 

 is also able, under favorable conditions, to reverse its action, and syn- 

 thesizes ethyl butyrate, for instance, from alcohol and butyric acid. 

 Hanriot 6 states that lipase can form monobutyrin from butyric acid 

 and glycerin and the higher the molecular weight of the acid the more 

 easily is the synthesis accomplished. Such facts indicate a most 

 important and far-reaching physiological role for the enzyme, as is 

 discussed at length by Loevenhart, who finds it in considerable 

 quantities wherever fat synthesis is taking place in the living tissue, 

 as in the subcutaneous fat and in the secreting mammary gland. 

 Between the enzyme studied by Loevenhart, in the milk gland, and 

 that occurring in milk, Gillet^ finds a most important difference, 

 namely, that the latter splits monobutyrin but not ordinary fats. In 

 accord with such a tram of thought comes the work of Connstein, 

 Hover, and Wartenberg, e who found a great variation in the ability 

 of lipase to split fats from different sources. Butter is very resistant, 

 owing, probably, to its high percentage of acids of low molecular 

 weight, since triacetin gave 0.4 per cent, tributyrin 9.5 per cent, and 

 triolein 50.6 per cent of free fatty acid when all were treated under 

 like conditions. It is also noteworthy that the reaction is much more 



a Concerning Lipase, the Fat Splitting Enzyme, and the Reversibility of its Action, 

 Amer. Chem. J., 1900, 24: 491. 



& Stir la reversibilite des actions diastatiques. Comptes rend. soc. biol.. 1901. p. 70. 



cAmer. J. Physiol... 1901-2, 6: 351. 



d Exist e-t-il une lipase dans le lait? — J. physiol. pathol. general, 1903. 



e The Enzymic Decomposition of Fat. Abs. J. Soc. Chem. Ind.. 1902, 21: 1541. 



