THE COLLOIDAL BEHAVIOR OF EDESTIN. 



By DAVID I. HITCHCOCK. 

 {From the Laboratories of The Rockefeller Institute for Medical Research.) 



(Received for publication, April 1, 1922.) 



I. 



INTRODUCTION. 



It has been shown in a series of papers by Loeb^ that the physical, 

 chemical, and so-called colloidal properties of solutions of the proteins, 

 gelatin, egg albumin, and casein, can be simply explained by two 

 general principles. The first of these is that proteins are amphoteric 

 electrolytes, reacting stoichiometrically with acids and bases to form 

 salts capable of electrolytic dissociation; the second is the principle 

 of Donnan's membrane equilibrium,^ which is set up when two solu- 

 tions are separated by a membrane impermeable to one ion of one of 

 the solutions. 



The present investigation was undertaken with the object of finding 

 out whether these laws would explain the behavior of solutions of a 

 protein of a difi'erent class; namely, a globulin. The globulin selected 

 for the purpose was edestin ; and it was found that its solutions obeyed 

 the same laws which had been shown to apply in the case of the 

 other proteins. 



The edestin used in these experiments was prepared from ground 

 hemp-seed by the method of Osborne,^-* with slight modifications. The 

 hemp-seed meal was extracted three times with 10 per cent sodium 

 chloride solution at 60°C., without previously extracting the oil. 

 The edestin was precipitated by dilution and recrystallized once from 

 sodium chloride solution according to Osborne. The substance was 



> Locb, J., Proteins and the theory of colloidal behavior, New York and London, 

 1922; J. Gen. Physiol., 1918-22, i-iv. 



* Donnan, F. G.,Z. Elcklrochem., 1911, xvii, 572. 



« Osborne, T. B., /. Am. Chcm. Soc, 1902, xxiv, 28, 39. 



* Osborne, T. B., Aider halden^s Uandb. d. biochem. Arbeitsmelhoden, 1910, ii, 289. 



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