Lii'Asi-: 77 



sugar coinbustiou that is iionnally a('r()in|)lished. 0. Coliiiheim '^^ at- 

 toinjited to explain the failures by his observation that the panereas 

 ])roduees a substanee that aetivates an inactive glycolytic en/ynie in 

 the muscles, liver, and probably in other organs. This work has been 

 much contested, and is not generally accepted, so we are still in the 

 dark as to how the carbohydrate oxidations are accomplished. (See 

 Cliai)ter xxii.) 



LIPASE n 



Lipase is probably present in greater or less amount in ail cells. 

 In the discussion of the reversible action of enzymes, on a previous 

 page, the modern conception of fat metabolism has been exi)lained, 

 which considers it to depend upon the existence of lipase in the cells 

 and fluids throughout the body. On account of the technical diffi- 

 culties in the w^ay of using higher fats, such as triolein, in experi- 

 2uental work, the esters of lower fatty acids have generally been used, 

 particularly ethyl butyrate, salicylic acid esters, and glycerol triace- 

 tate. Enzymes splitting ethyl butyrate, and presumably higher fats, 

 have been demonstrated in practically all tissues examined ; the names 

 of Kastle and Loevenhart in this country, and Hanriot in France, 

 being particularly connected with this work. Whether in all cases 

 the presence of this reaction is proof positive of the presence of an 

 enzyme splitting fats, a true "lipase," is not yet known. JMuch of 

 the work so far reported on the occurrence of lipase in tissues is of 

 questionable value, especially as to quantitative results, because of 

 faulty methods. Saxl ^■"' points out and avoids some of these errors, 

 and finds that during autolysis of tissues the splitting of the natural 

 fats present in the cells is but slight ; simple esters are attacked more, 

 especially amyl-salicylate ; muscle and blood are the least active 

 tissues. Most authors agree that lymphoid cells are especially rich in 

 lipolytic enzymes.^' In the serum of normal individuals the esterase 

 content seems to be quite constant,^"'^ and Quinan ^-'^ found the tissue 

 content also constant, the liver containing about twice as much as 

 the kidney and over three times as much as the muscle. He states 

 that different parts of the brain have characteristic lipase activity 

 (but^-rase).^'"' Thiele ^"'^ has found that blood, chyle, and various 

 tissues also contain an enzyme which can hydi'olyze lecithin, but except 



isaZeit. phvsiol. Cliem., 1903 (39), 330; also see Simpson, Bioclicin. .l..ur.. 1910 

 (5), 126. 



i-t For literature on lipase see Connstein, Ergebnisso Pliysiol., 1904 (3. Aht. 1), 

 194; concerning the behavior of lipase see Taylor, Jour. Biol. Cheni., 1906 (2), 

 103: Fali<, Proc. Natl. Acad., 1915 (1), ]3(i. 



isBiochem. Zeit., 1908 (12), 343. 



1" The distribution of lipases in difTerent species of animals and their various 

 organs has been investigated bv Porter, Miinch. med. Woch., 1914 (61). 1774. 



isaSagal, Jour. Med. Pes., 1916 (34), 231. 



^shJMd., 191.5 (32), 45. 



15c Ibid., 1916 (35), 79. 



isdBiocliem. Jour., 1913 (7), 275. 



