DENATURING OF VEGETABLE PROTEINS 41 



in edestin, and it may be that in the formation of edestan a slight loss 

 of nitrogen occurs. The difference, however, between these analyses 

 is too slight to warrant a definite conclusion on this point. 



The edestan, thus prepared for analysis, is a voluminous white 

 powder which swells somewhat in water and forms a colourless, trans- 

 parent jelly with very dilute hydrochloric acid. In the dry state it is 

 slightly, if at all, soluble in strong ammonia, but the gelatinous mass 

 formed by treating the substance with very dilute hydrochloric acid is 

 slightly soluble therein and yields a solution which gives a precipitate 

 with ammonium chloride. Consequently when hydrochloric acid is 

 added to its ammoniacal solution a precipitate forms, even when much 

 of the ammonia is still unneutralised. The ammoniacal solution is not 

 precipitated by sodium chloride. 



Edestan exists in preparations of edestin chloride in combination 

 with acid. The amount of acid required to form a compound sparingly 

 soluble in water appears to be definite, as the following experiments 

 show. A quantity of edestan obtained from a preparation of edestin 

 chloride was suspended in water and dialysed until free from chloride. 

 The dialyser then contained an opalescent fluid and a voluminous 

 precipitate. The acidity of the substance dissolved in this solution 

 was found in two experiments to correspond to 21-5 and 23-4 c.c. of a 

 centinormal solution per gramme. Other experiments gave similar 

 results, from which it appears that the acidity of the edestan chloride 

 was almost exactly three times that of the edestin chloride insoluble in 

 water or one and one-half times that of the edestin chloride soluble 

 therein. From these results we may conclude that the basic property 

 of this altered product is greater than that of the original protein, and 

 as this substance originates so readily and in such large proportion in 

 the presence of a small amount of free acid, it is evident that ex- 

 periments which have been made to determine the acid-combining 

 power of proteins, in which an excess of acid has been employed, 

 do not necessarily show the acid-combining power of unchanged 

 proteins. 



The reactions of edestan are similar to those which are considered 

 to be characteristic of the histone group, but there is manifestly no 

 connection between this substance and the true histones. The globin 

 obtained from haemoglobin by the action of dilute acids is generally 

 designated a histone on the ground of the similarity of the reactions 

 of the two substances. It is possible, if not probable, that globin more 

 nearly resembles edestan than the true histones and that it is a similar 

 product of alteration of the protein constituent of the haemoglobin 



