38c APPENDIX. 



SOME PEODUCTS OF TEYPTIC PROTEOLYSIS— LYSIN, 



LYSATIN. 



In Lesson X,, 5, Leucin and Ty rosin are stated to be products formed by the 

 action of the tryptic enzyme on proteids. These substances, as well as others, 

 viz., aspartic acid and glutamic acid, have long been known as decomposition 

 products of vegetable proteids, e.g., as cleavage products by boiling w th 

 dilute acids. Aspartic acid is amido-succinic acid, COOH.CH2CH(NH2). 

 COOH, and is also a product of pancreatic digestion of fibrin, while glutamic 

 acid, COOH. C3H5(NH2). COOH, is amido-pyrotartaric acid. Both acids 

 belong to the fatty acid series. 



Drechsel has recently discovered two new nitrogenous bases — lysin and 

 lysatinin or lysatin — products of the decomposition of proteids {e.g., casein, 

 gelatin, egg-albumin) when the latter are boiled with HCl and stannous 

 chloride. These bodies result from the simple hydroly tic cleavage of the proteid 

 molecule, and it has recently been shown by Hedin that they are also formed 

 in trypsin -proteolysis. 



Lysin, C6H14N2O2, is a diamido-caproic acid, and is a representative of the 

 fatty acid group, and has intimate chemical relationships with leucin. 



Lysatinin or Lysatin, CgHjaNgO.. — Its composition is less accurately known, 

 but it has the composition of a creatin. The special interest which attaches 

 to this body is that, as a product of trypsin -proteolysis, it can by simple 

 hydrolytic decomposition break down into urea. Thus trypsin-proteolysis 

 yields cleavage products, from one or more of which conies the substance lysatin, 

 which behaves like creatin in this respect, viz., that when boiled with baryta- 

 water, it yields sarkosin and urea. Thus chemists have found a series of 

 cleavage products the result of hydrolytic decomposition between proteid and 

 urea. (Chittenden, Digestive proteolysis^ p. 103, New Haven, 1895. Cartwright 

 Lectures.) 



