Till BIOI BEMICAL PROl - ■ : ION 19] 



The importance of the presence of erepsin in the mucous membri 

 of the intestine is thai it serves as a barrier to the pat ny unsplil 



amino acids from the intestinal contents into the blood. It insures the 

 breaking up of the protein molecule into its ultimate units I 

 lion. The further fate of the absorbed amino acids will he considi 

 under the subject of protein metabolism. 



'I'm \> tion op Lipase 



Neutral t';it is decomposed into fatty acids and glycerine by tin 1 lij> 

 presenl in the pancreatic juice. This enzyme may also 1"' extracted from 

 the glands by means of 'i'l per cent alcohol. Its action is remarkably 

 accelerated by the presence of I>il<'. and considerably depressed by i' 

 ganic suits. It is ;iisn very dependenl on the degree of alkalinity, the 

 optimum being a hydrogen-ion concentration of II x 1"". The favoring 

 action nt' bile is undoubtedly owing to the bile salts (see pj ; . and 



it is probable that tins action is dependenl upon the influence which 

 those have in lowering surface tension ami therefore brinL r iiiL r about a 

 more intimate contad between fat and water. 



Tin: Action of A.mtlopsin 



The action of pancreatic juice mi carbohydrates depends on the 

 amylolytic enzyme called <nniihii>sin. In animals having no active ptyalin 

 in the saliva, amylopsin serves as the only diastatic enzynn ncerned 



in the digestive process. In any case, at least for the first Btag the 



disruption of the starch molecule that is, its conversion into dextrines 

 amylopsin is a more powerful enzyme than ptyalin. It does not appear 

 to he so efficienl ;is ptyalin in the final stages of the hydrolj r it 



does not produce so much reducing sugar as ptyalin does. Indeed 

 tracts of pancreas will sometimes convert starch into soluble starch and 

 dextrine with greal speed, bul produce scarcely any reducing sugar. 

 On this account it is believed by many investigators thai there are al l< 



two distinct and separate enzymes in amylopsin and also perhaps in 

 ptyalin, one a tine amylase, which converts starch into dextrine, and 



the other a dextrin ase, which converts dextrine into maltose. In 



case of both ptyalin and amylopsin digestion proceeds besl i 1 : 

 weak acid reaction. Amylopsin, as it d in the p 



is fully activated: bile, apart from the alkali which 

 no influence on its digestive power. 



Besides amylopsin the pancreatic juice also eontai in 



the case of young animals or of those that take milk with their f 

 throughoul their lives, lactase also. \\\, rkling animal 1 



