ENZYMES CONCERNED WITH DIGESTION OF LIPIDS 15 



cerned, the relative potency is highest for the rat, followed in order by 

 rabbit, beef, and human tissues. 55 Esterases have been found in high 

 concentration in all tissues of the carp; here again, the largest amount was 

 found in the liver. 85 Gomori, 86 using a histochemical method, reported 

 that adipose tissue of the rat and rabbit possessed lipolytic activity. 

 Renold and Marble 87 later demonstrated that lipolysis obtained not only in 

 the subcutaneous adipose tissue of rats, but also in that of man. The rate 

 of lipolysis in intra-articular fat was only one-third that of the subcutaneous 

 fat in the case of man. The levels of lipase were higher in females than m 

 males; in diabetic males, the concentration of enzyme was only one- 

 fourth that found in diabetic females. No correlation between sex, age, or 

 food intake and lipolytic activity of adipose tissue was observed in rats. 



(a) The Presence of Several Esterases in Liver and Pancreas. Falconer 

 and Taylor 88 were able to demonstrate that pig liver contained two different 

 esterases. Hofstee 89 reported two esterases in pancreatic tissue, desig- 

 nated Esterase I and Esterase II, both of which are distinct from steapsin. 

 Both esterases were shown to be best adapted to esters with a carbon chain 

 not shorter than 4 and not longer than 8 atoms. In the case of Esterase I, 

 the "affinity" constants from the C 5 to C 8 compounds are about the same, 

 and the activity drops sharply beyond these limits. The affinity constant 

 of Esterase II doubles with each additional carbon between C 5 and C 8 . 



(b) Serum Esterase. The presence of lipase has been demonstrated in 

 blood serum. It has been shown that esterase resembling liver esterase also 

 occurs in this fluid. Hanriot 90 was the first to discover "lipase" in serum 

 which hydrolyzed monobutyrin. Aldridge 91 indicates that the serum 

 esterases of many species may be separated into two distinct types, which 

 he designates as .4-Esterase and 5-Esterase. Whereas the A-type is not 

 inhibited by E600 (diethyl-p-nitrophenyl phosphate) and hydrolyzes p- 

 nitrophenylacetate more rapidly than p-nitrophenylbutyrate, the B- 

 enzyme is inhibited by a concentration of 10~ 7 to 10~ 8 M of E600; more- 

 over, the speed of hydrolysis of the p-nitrophenyl esters is reversed. 



Serum esterase acts principally as a tributyrinase. The tributyrinase 

 activity of intestinal lymph has been shown by Flock and Bollman 92 to be 



85 J. C. Kernot and H. W. Hills, Z. physiol. Chem., 208, 33-39, 39-42 (1932). 



86 G. Gomori, Arch. Pathol, 41, 121-129 (1946). 



•» A. E. Renold and A. Marble, J. Biol. Chem., 185, 367-375 (1950). 



88 J. S. Falconer and D. B. Taylor, Biochem. J., 40, 831-834 (1946). 



89 B. H. J. Hofstee, J. Biol. Chem., 199, 365-371 (1952). 



90 Hanriot, Compt. rend. soc. biol, 48, 925-926 (1896). 



91 W. N. Aldridge, Biochem. J., 53, 110-117 (1953). 



92 E. V. Flock and J. L. Bollman, J. Biol. Chem., 185, 903-908 (1950), 



