CHAPTER XIV 



OPTICAL PROPERTIES OF PROTEIN SOLUTIONS* 



1. The Specific Rotatory Power of the Proteins. — It was 



observed by Hoppe-Seyler (16) (18) that the majority of animal 

 proteins, in aqueous solutions, rotate the plane of polarized light 

 to the left, and he measured the specific rotatory powers of several 

 of the animal proteins. These investigations were continued by 

 Fredericque (7) and Klihne (26) who proposed employing the 

 specific rotatory power of a protein as a means of characterizing 

 it and establishing its identity. The results which were obtained 

 by these observers have been greatly extended and amplified by 

 a large number of observers who have investigated this physical 

 property of a variety of proteins. It appears that all of the 

 natiu-ally occurring proteins, excepting the nucleo-proteins and 

 haemoglobin, rotate the plane of polarized light to the left. The 

 following are among the results which have been obtained by 

 observers who have worked with proteins of animal origin: 



TABLE I 



Protein 



Serum albumin 



Serum albumin 



Serum albumin 



Serum albumin 



Serum albumin 



Egg albumin 



Egg albumin 



Lact-albumin 



a-crystallin from the crystalline 

 lens 



Observer 



Hoppe-Seyler (20) 

 Fredericque (7) 

 Starke (62) 

 Sebelien (59) 



Maximovitsch (31) 

 F. G. Hopkins (15) 



Osborne and Camp- 

 bell (38) 

 Sebelein (59) 



Morner (33) 



Nature of solution 



m water 



dialyzed solution 

 in distilled water 



dilute ammonium 



sulphate 

 water 



dialyzed solution in 

 distilled water 



neutral solution in 

 dilute ammonia 



Degrees 



-56.00 

 -57.30 

 -60.05 

 -60.10 to -62.60 



-47.47 

 -30.70 



-28.60 to -30.80 



-36.40 to 36.98 



-46.90 



* The opalescence of protein solutions has already been discussed (Chap 

 XIII, 8). 



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