ON THE ELECTRICAL CHARGE OF PROTEIN. H7 



Let us consider, first of all, the precipitation of native 

 prote'n through neutral salts of the alkali metals and see 

 in how far the ions play an immediate role. The follow- 

 ing table, in which + indicates that the protein is pre- 

 cipitated, that it is not precipitated, gives a good survey 

 of these relations. 



In the vertical row of the table are arranged the positive 

 ions in the order of their decreasing power to precipitate 

 protein; in the horizontal row are arranged the negative 

 ions in the order in which they inhibit the precipitation. 



! 



Increase in inhibition. 



The antagonism between cation and anion is indicated 

 by the appearance of one and the same ion in salts which 

 precipitate and those which do not precipitate protein 

 for example, sodium as the sulphate and as the bromide; 

 and if we go along still further in the sodium series the in- 

 hibiting effects of iodide and sulphocyanate ions have so 

 much the upper hand that the presence of these salts pre- 

 vents the precipitation of protein through other salts. As 

 an actual matter of fact, the inhibiting salts were discov- 

 ered as a consequence of the assumption of antagonistic 

 ion effects. That it is the positive metallic ions which are 

 the bearers of the precipitating power may be concluded 

 from the fact that native protein carries a negative charge. 



