154 THE PROTEIN SUBSTANCES. 



On boiling with dilute caustic soda, with the taking up of water, the 

 sodium salt of indoxyl-a-benzoylaminoacrylic acid, 



C 8 H 6 N. CH:C.NH.COC 6 H 5 

 COONa 



is obtained, from which by reduction and splitting off of the benzoyl 

 group by the action of sodium alcoholate the tryptophane is obtained: 



C 8 H 6 N.CH : C.NH.COC 6 H 5 



| +H 2 +H20=C 8 H 6 N.CH 2 .CH.NH 2 + C 6 H 5 COOH. 



CCOH COOH 



The trytophane formed in digestion is /-tryptophane, which is levoro- 

 tatory in aqueous solution (HOPKINS and COLE). Racemic d-Z-trypto- 

 phane has also been obtained by digestion in certain cases by ALLERS 

 and J^EUBERG; this is probably formed from the /-tryptophane (ABDER- 

 HALDEN and L. BAUMANN 1 ), which very readily undergoes racemization. 



Tryptophane crystallizes in silky, rhombic or six-sided leaves. It 

 does not have a sharp melting-point, and according to the rapidity of heat- 

 ing melts at 252, 273 and 289, according to various authorities. 

 Tryptophane is readily soluble in hot water, difficultly soluble in cold 

 water, and only slightly soluble in alcohol. The solution of cW-trypto- 

 phane has a faint sweetish taste, and /-tryptophane a faint bitter taste. 

 The statements as to the optical behavior of tryptophane differ some- 

 what (HOPKINS and COLE, NEUBERG and POPOWSKY, ABDERHALDEN 

 and KEMPE, ELLINGER and FLAMAND, H. FISCHER 2 ) which, according 

 to ABDERHALDEN, is probably due to the readiness with which it under- 

 goes racemization. According to ABDERHALDEN and L. BAUMANN, 

 at 20 C. the aqueous solution has a rotation of (a) D = 30.33. HOP- 

 KINS and COLE give (a) D = 33 for the watery solution. It is dextro 



N N N 



rotatory in or NaOH as well as in HC1. 

 1 2i 1 



Tryptophane yields indol and skatol when sufficiently heated. It gives 

 the ADAMKIEWICZ-HOPKINS 3 reaction and a rose-red color on the addi- 

 tion of chlorine or bromine water (tryptophane reaction). The compound 

 produced in this last reaction contains, according to NEUBERG, 4 1 atom 

 of bromine (or chlorine) while another compound containing 3 

 halogen atoms is yellow in color. If a pine stick previously moistened 



1 R. Allers, Biochem. Zeitschr., 6; C. Neuberg, ibid., 6; Abderhalden and Baumann, 

 Zeitschr. f. physiol. Chern., 55. (Literature on the specific rotation.) 



2 See Abderhalden and Baumann, Zeitschr. f. physiol. Chem., 55 (literature). 



3 In regard to this reaction see also Dakin, Jourri. of Biol. Chem. 2, and O. Rosen- 

 heim, Biochem. Journ., 1. 



4 Biochem. Zeitschr.. 2 and 6. See also Levene and Rouiller, ibid., 4. 



