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 Ktihne (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 

 naturally 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 



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

 XIII, 8). 



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