16 



Mr. E. G. Young. On the Optical Rotatory 



BaCl2, Willcock claims that a very much greater sensitivity can be obtained ; 

 and by employing this method, specific rotations of different albumin crystalli- 

 sations were found to vary considerably. If that fact were true, the biological 

 chemist would still be without a means of recognising a chemical individual 

 of the protein group, even if be had isolated one. 



The experimental history as described in the following pages was developed 

 with the object of discovering whether a constant specific rotation could be 

 obtained for crystalline ovalbumin, and what was the relation between the 

 hydrogen ion concentration and the optical rotation with reference to the iso- 

 electric point. It was thought that such a study might yield an explanation 

 of the variability of the rotatory power and possibly some direct evidence on 

 the question of a tautomeric equilibrium in the protein molecule. These 

 experiments are described first. The investigation was extended to a study 

 of the conditions governing the preparation of a pure crystalline serum 

 albumin and the properties of this substance examined. 



Experimental. 

 The Specific Rotation of Crystalline Ovalbumin. 



The values obtained for the specific rotation of hen ovalbumin by different 

 observers at different times and with material under somewhat different 

 physical conditions have been recorded in Table I. The earlier determina- 

 tions on amorphous material are interesting in that they show a higher value 

 than that observed for crystalline material. Osborne and Campbell (1900) 

 have shown chat the non-crystallisable albumin, which they have called 

 conalbumin, has a higher value for »[«]d than the crystalline, and contamina- 

 tion by this substance probably explains the higher value. 



Table I. 



Observer. 



Material. 



Specific rotation. 



Haas (1876) 



Amorphous 



-38 -08 



Panormoff (1898) 





-36 -2 



PanormofE (1898) 



Crystalline 



-23 -6 



Worms (1898) 





-26 -1 



Bondzynski and Zoja (1894)... 



>) 



-26 -0 to -42-54 



Osborne (1899) 





-28 -42 



Osborne and Campbell (1900) 





-28-60 to —30 -80 



Hopkins (1900) 



>> 



-30 -7 



Willcock (1908) 





-30-3 to -31 6 



Only the last three determinations are of importance, as they were made 

 on similar material which had been recrystallised several times, and of these 



