10 II. DIGESTION AND ABSORPTION OF FATS 



more pronounced in augmenting the hydrolysis of triglycerides than in 

 increasing that of the monovalent alcohol monocarboxylic acid esters. 39 



Gomori 40 reported that water-soluble unsaturated fatty acid esters are 

 hydrolyzed almost exclusively by the lipase of the pancreatic type (true 

 lipase), while similar esters containing saturated acids are attacked by 

 esterases of both the hepatic and the pancreatic types. Moreover, Ravin 

 and Seligman 41 stated that the specificity of a substrate for lipase is de- 

 pendent not only upon the chain length of the acyl group but also upon the 

 number of ester groups present in the substrate. The structure of the lipid- 

 water interface of the emulsions formed by the esters is believed to be 

 correlated in a regular manner with their chemical structure; this acts as 

 an additional determinant of the specificity of lipase, by offering steric 

 hindrance to ali-esterase. Tributyrin, which is widely used for the deter- 

 mination of "serum lipase," does not have a sufficiently high degree of speci- 

 ficity to fulfill the necessary criteria. On the other hand, 2-naphthyl 

 laurate has a high specificity for lipase, and this is satisfactory as a sub- 

 strate for the determination of serum lipase. 41 



c. Intestinal Lipase. The intestinal walls have been shown to produce 

 a lipase which is likewise activated by bile. Schiff 42 found a lipase in the 

 intestinal contents of depancreatized dogs. However, it is possible that the 

 hydrolysis produced by this preparation may have been due to the effect 

 of gastric lipase. On the other hand, it was later reported that intestinal 

 juice obtained from dogs having a Thiry-Vella fistula has a weakly hydro- 

 lytic action. 43,44 Kalaboukoff and Terroine, 45 using glycerol, were able to 

 prepare an active lipase from the intestinal mucosa, the activity of which 

 was accelerated by the bile acids. 



d. Serum Lipase. The lipolytic action of serum is ascribed in part to 

 the presence of a lipase and partly to that of esterase. The lipase origi- 

 nates from the pancreas, while the blood esterase is manufactured in the 

 liver. The difference in origin of these enzymes was beautifully demon- 

 strated by Hiruma, 46 who found that ligation of the pancreatic duct in- 

 creased blood lipase ; Cherry and Crandall 47 also noted that, although lipase 

 is normally absent from the blood, it appears after ligation of the pancreatic 



39 P. J. Fodor, Arch. Biochem., 30, 197-201 (1951). 



« G. Gomori, Proc. Soc. Exptl. Biol. Med., 72, 697-700 (1949). 



« H. A. Ravin and A. M. Seligman, Arch. Biochem. Biophys., 42, 337-354 (1953). 



42 M. Schiff, Arch, physiol norm, path., [5], 4, 699-702 (1892). 



43 W. Boldyreff, Zentr. Physiol, 18, 457-460, 460-461 (1904). 



44 W. Boldyreff, Z. physiol. Chem., 50, 394-413 (1907). 



45 L. Kalaboukoff and E. F. Terroine, Compt. rend. soc. biol, 59, 617-619 (1907). 



46 K. Hiruma, Biochem. Z., 139, 336-341 (1923). 



47 1. S. Cherry and L. A. Crandall, Jr., Am. J. Physiol, 100, 266-273 (1932). 



