Sect. V, 1922 [79] Trans. R.S.C. 



XIV. The Qtiestion of the Presence of the Tryptophane Radicle in the 



Molecule of Hemoglobin 



By Andrew Hunter, M.A., F.R.S.C, and Henry Borsook, B.A. 



(Read May Meeting, 1922) 



It has been stated recently by Fiirth and Lieben^ that the hemo- 

 globin molecule entirely lacks the radicle of tryptophane. Since the 

 other blood proteins are fairly rich in that amino-acid the purity of 

 any specimen of hemoglobin (or of its protein component) might, if 

 Fiirth and Lieben's claim be justified, be very conveniently controlled 

 by the outcome of the delicate and characteristic glyoxylic reaction. 

 We have attempted lately to apply this criterion to a number of 

 specimens of globin from horse blood, regarding which we desired to 

 have some assurance that they were free from contamination with 

 the other blood proteins. To our surprise and disappointment every 

 specimen, no matter how thoroughly, to our thinking, it had been 

 purified, gave a positive reaction. We have, therefore, been led to 

 inquire whether tryptophane is not, after all, in spite of Fiirth and 

 Lieben's opinion, an actual component of globin. 



A solution of horse oxyhemoglobin was obtained by taking a well 

 washed mass of corpuscles, and treating the product with alumina 

 cream for the removal of serum proteins. From a portion of this 

 solution oxyhemoglobin in crystalline form was prepared by the 

 alcohol method. The product was then four times recrystallized. 



Globin was prepared from (a) the original oxyhemoglobin 

 solution, (&) the fourth crystallization, (c) the fifth crystallization. 

 All three specimens gave a positive, and indeed quite marked, glyoxylic 

 reaction. It was argued that if this were to be attributed not to the 

 globin itself, but to another protein contaminating the hemoglobin 

 from which it had been prepared, the reaction should at least become 

 feebler with each succeeding attempt at purification. To determine 

 whether or not this occurred we applied the glyoxylic test in such a 

 manner as to yield a rough estimate of the quantity of tryptophane 

 actually present. 



Standard solutions of tryptophane were prepared, of concentra- 

 tions ranging, by steps of 0.01, from 0.01 to 0.1%. Each sample of 

 globin was then dissolved in N/10 HCl in a concentration of 1 per cent. 

 Two c.c. of each standard and of each globin solution were treated 



iFiirth and Nobel: Biochem. Zeitschr., cix, p. 103 (1920). 



