CLEAVAGE PRODUCTS OF PANCREATIC DIGESTION 407 



20. Artificial Pancreatic Juice. Artificial pancreatic juice can be 

 prepared from the pancreas by grinding and macerating and extracting a 

 pancreas with water or glycerin, as described for the gastric glands in Experi- 

 ment ii above. Commerical preparations of pancreatic enzyme can be 

 obtained on the market. A solution of a glycerin extract of pancreatic gland 

 or of commercial pancreatin in o . 2 per cent, sodium carbonate is known as 

 artificial pancreatic juice. 



21. The Enzymes of Pancreatic Juice. The pancreatic juice con- 

 tains enzymes which exert a digestive action on starches, fats, and proteins. 

 This fact can be tested as follows: a, to 5 cc. of artificial pancreatic juice 

 add 2 cc. of i per cent, starch paste, mix and set in the water-bath at 40 C.; 



b, to i cc. of pancreatic juice (artificial juice is not active), collected in Ex- 

 periment 17, add 0.5 cc. of neutral olive oil, and place over a water-bath; 



c, to 5 cc. of artficial pancreatic juice add a few flocks of fibrin. Test the 

 digestive action on starch by the iodine test for the disappearance of starch, 

 or by the copper-reduction test for the presence of reducing sugar. Test the 

 fat by its reaction, noting that the neutral or slightly alkaline solution has 

 become acid, also by the fact that an emulsion has been formed. Note that 

 the protein has gone into solution. 



The digestive action on starch is due to the enzyme amylopsin, or pan- 

 creatic diastase, as it is sometimes called. The fat-splitting effect is due to the 

 enzyme lipase, and the solution of the fibrin is accomplished by the proteolytic 

 enzyme, trypsin. 



22. Conditions which Influence the Action of the Enzymes of 

 Pancreatic Juice. Prepare each of 5 test-tubes, a, b, c, d, e, as shown in 

 the table on the next page. Place a, b, c, d in the water-bath at 40 C. , and 

 e into an ice-bath. Add to each tube 2 cc. of i per cent, starch paste. Follow 

 the digestive changes by the tests previously outlined and tabulate the results. 



Repeat this experiment with a second set of test-tubes containing 4 

 threads of fibrin in each. Lipase is not very active in artificial pancreatic 

 juice and may be omitted, but if pancreatic juice is available make a third 

 set containing fat. 



23. Cleavage Products of Pancreatic Digestion. To 400 cc. of arti- 

 ficial pancreatic juice add 25 grams of moist fibrin and place in a water-bath 

 at 40 C., add 2 cc. of chloroform or of thymolin alcoholic solution to 

 prevent putrefactive changes. After three or four hours filter off 100 cc. 

 and place the remainder on the water-bath for one or two days. Test the 

 filtrate for alkali ablumin, albumoses, and peptones by the method outlined 

 in Experiment 14 above. 



Filter the second portion and concentrate to a syrupy mass on the water- 

 bath. Crystals make their appearance. Pour off the fluid, wash the crystals 

 with cold water, and examine under the microscope for sheaves of tyrosin. 

 The filtrate contains leucin. 



