vi AMPHOTERIC NATURE OF ALBUMINS 217 



thus alanin is approximately neutral, while methylene-alanin is 

 strongly acid : 



CH q CBL 



I I 



CH.NH, CH.N 



I I 



COOH COOH 



Alanin. Methylene-alanin. 



The presence of a second NH 2 or COOH group does not alter the 

 general character of an amino-acid, but the basic character pre- 

 dominates in lysin, and the acid character in glutaminic acid, but not- 

 withstanding this the latter can act as a base, for it forms chlorides. 



Albumins behave in exactly the same way as do the ammo-acids. 

 According to Sjoqvist, 1 Cohnheim, 2 Cohnheim and Krieger, 3 Erb, 4 

 Bugarszky and Liebermann, 5 and von Rhorer, 6 albumins react as bases 

 towards acids, being in some cases even more basic than the amino-acids 

 (see below). According to von Rhorer albumins are about 500 times 

 more basic than is distilled water, and according to Sjoqvist about 

 74 '2 times more feeble than is anilin. With acids they form salts 

 which undergo great hydrolysis. ' 



According to Erb the hydrolysis of the chlorides of albumins 

 amounts to 88 per cent, and is probably even greater. Arrhenius 

 and Ley 7 and others have' further shown that the hydrolysis is not a 

 constant factor, because, apart from temperature, it varies with the 

 absolute and the relative amounts of the albumin and the acid present. 

 Thus the greater the concentration of, for example, albumin-chloride, 

 the less is its hydrolysis, so that dilute solutions contain more free 

 hydrochloric acid and less albumin -chloride than do concentrated 

 solutions. If, on the other hand, there is present more hydrochloric 

 acid than is needed for rectifying the basic tendencies of an amino- 

 acid or an albumin, hydrolysis is diminished ; with a large excess of 

 hydrochloric acid hydrolytic dissociation is nearly absent, while hydro- 

 lysis amounts to 80-90 per cent if acid and albumin are in equivalent 

 solutions. Erb has studied these phenomena most minutely on pure 

 albumins : serum-albumin, egg-albumin, edestin, and hetero-albumose. 



1 J. Sjoqvist, Skandinav. Arch. f. Physiol. 5. 277 (1894) (here the older literature 

 is given), 6. 255 (1895) ; Zeitschr. /. klin. Med. 32. 451 (1896). 



2 0. Cohnheim, Zeitschr. f. Biologie, 33. 489 (1896). 



3 0. Cohnheim and H. Krieger, ibid. 4O. 95 (1900). 



4 W. Erb, ibid. 41. 309 (1901). 



5 St. Bugarszky and L. Liebermann, Pfiugers Arch. f. d. ges. Phys. 72. 51 (1898). 



6 L. von Rhorer, ibid. 90. 368 (1902). 



7 H. Ley, Zeitschr. f. physikal. Chem. 30. 193 (1899). 



