14 II. DIGESTION AND ABSORPTION OF FATS 



Bacteria which tolerate low temperatures, such as strains of Achromo- 

 bacter and of the saprophytic, flagellated bacterium, Pseudomonas, as well 

 as certain bacilli, may contain lipases. 76 - 77 Rosenfeld 78 confirmed the exist- 

 ence of bacteria which effect anaerobic lipolysis; these include sulfate 

 reducers. The activity of these lipases is quite general. 



{2) Esterases 



Although the expression "esterases" should be considered as an all- 

 embracing term to include not only lipases but also a number of ester- 

 splitting enzymes which act on general and specific types of esters, or, in 

 fact, on individual esters, its usual connotation is solely to indicate the non- 

 specific group of enzymes whose behavior is of a general nature. The 

 esterases which attack aliphatic compounds have been called "ali-esterases" 

 by Richter. 79 



a. Origin of Esterases. Esterases are widely distributed in animal tis- 

 sues, but the highest concentration occurs in the liver. There is convinc- 

 ing evidence that the liver is the site of origin of the esterases, since the 

 amount present in this organ diminishes after hepatic injury brought about 

 by phosphorus or by chloroform. 80 Prewitt 81 likewise demonstrated that 

 this enzyme can be partially washed out of the organ by perfusion with 

 blood. 



Blood esterase would appear to have its origin in the fiver rather than in 

 the pancreas. On the one hand, no decrease in the level of esterase in the 

 blood obtains after pancreatectomy 82 while, on the other hand, blood ester- 

 ase values rise concomitantly with their decrease in the liver caused by such 

 hepatic poisons as phosphorus or chloroform. 80 



b. Distribution of Esterases. In addition to the liver, the lung and the 

 kidney contain an extremely active esterase, 83 while in small intestine and 

 spleen, the activity of the esterase preparations decreases progressively. 35,84 

 The esterases of brain and muscle exhibit only slight activity. Rat car- 

 cinoma esterase appears to have a feeble action. As far as species is con- 



76 L. B. Jensen and D. P. Grettie, Food Research, 2, 97-120 (1937). 



77 J. R. Vickery, J. Council Sci. Ind. Research, 9, 107-112, 196-198 (1936); Chem. 

 Abst.,30, 6779(1936). 



78 W. D. Rosenfeld, Arch. Biochem., 11, 145-154 (1946). 



79 D. Richter, Biochem. J., 36, 746-757 (1942). 



80 J. W. Jobling, A. A. Eggstein, and W. Petersen, J. Exptl. Med., 22, 706-712 (1915). 



81 P. V. Prewitt, Am. J. Physiol, 65, 287-294 (1923). 



82 C. L. von Hess, /. Biol. Chem., 10, 381-398 (1911). 



83 K. G. Falk and G. McGuire, J. Biol. Chem., 108, 61-71 (1935). 



84 H M. Noyes, K. G. Falk, and E. J. Baumann. J. Gen. Physiol, 9, 651-675 (1925- 

 1926). 



