GLYCOCOLL. 139 



3. The Amino-acids. 1 



|o I 



Glycocoll (amino-acetic acid), C 2 H 5 NO2 = _ !""' > also called gty- 



COOrl 



cine or gelatin sugar, is found in the muscles of the invertebrates, 

 but has chief interest as a hydrolytic decomposition product of protein 

 bodies, especially fibroin, spider-silk elastin, gelatin, and spongin, as 

 well as of hippuric acid and glycocholic acid. i 



Glycocoll forms colorless, often large, hard rhombic crystals or four- 

 sided prisms. The crystals have a sweet taste and dissolve readily in 

 cold water (4.3 parts). Glycocoll is insoluble in alcohol and ether and 

 dissolves with difficulty in warm alcohol. Like the amino-acids in gen- 

 eral it combines with acids and alkalies. With the latter compounds 

 we must mention those with copper and silver. Glycocoll dissolves 

 cuDric hydroxide in alkaline liquids, but does not reduce at boiling heat. 

 A boiling-hot solution of glycocoll dissolves freshly precipitated cupric 

 hydroxide, forming a blue solution, which in proper concentration deposits 

 blue needles of copper-glycocoll on cooling. The compound with hydro- 

 chloric acid is readily soluble in water but less soluble in alcohol. 



SORENSEN 2 finds that phosphotungstic acid does not precipitate 

 glycocoll from dilute solutions but only from concentrated ones. By the 

 action of gaseous HC1 upon glycocoll in absolute alcohol, beautiful 

 crystals are obtained of the hydrochloride of glycocoll-ethyl ester, which 

 melts at 144 C. and from which the glycocoll-ethyl ester can be obtained 

 by the method suggested by E. FISCHER 3 for the separation of glycocoll 

 from the other amino-acids. On shaking with benzoyl chloride and 

 caustic soda, hippuric acid is formed, and this is also made use of in 

 different ways in detecting and isolating glycocoll (Cn. FISCHER, GON- 

 NERMANN, SpiRO 4 ). The j3-naphthalene-sulpho-glycine with a melt- 

 ing-point of 159, the 4-nitro-tolulene-2-sulpho-glycine, melting at 180, 

 and the a-naphthylisocyanate compound melting at 190.5-191.5 are 

 also of importance. On putrefaction methane is probably produced 

 from glycocoll. 



Glycocoll can be best prepared from hippuric acid by boiling it with 

 4 parts dilute sulphuric acid (1:6) for ten to twelve hours. After cooling 



1 In regard to the division of the amino-acids among the three chief groups of 

 organic compounds we refer to pages 85-86. 



2 Meddelelser, fraa Carlsberg-laboratoriet, 6, 1905. 



3 Ber. d. d. chem. Gesellsch., 34. 



4 Ch. Fischer, Zeitschr, f. physiol. Chem., 19; Spiro, ibid., 28; Gonnermann, 

 Pfliiger's Arch., 59. 



