GENERAL CHEMICAL CHARACTERS OF PROTEINS 45 



in pathological cases. Cane-sugar on hydrolysis is converted into a 

 mixture of glucose and fructose according to the equation 



C 12 H 13 O n + H 2 = C 6 H 12 6 (glucose) + C 6 H 12 O 6 (fructose), 



whilst methyl acetate is converted by hydrolysis into a mixture of 

 methyl alcohol and acetic acid : 



CH 3 . COOCH 3 + H 2 O = CH 3 . COOH + CH 3 . OH. 



The rate at which these reactions take place is proportional to 

 the concentration of the hydrogen ions present (i.e., in sufficient dilu- 

 tion of the acid), when the same amounts of ester or sugar are 

 employed in comparative estimations. If combination between acid 

 and protein take place the addition of the latter will diminish the 

 effective concentration of the former. 



If now two parallel experiments be carried out with the same 

 concentrations of sugar or ester, both in the presence of known (but 

 not necessarily the same) concentrations of acids, but one in the 

 presence of known amount of protein and the other without, then 

 according to Wilhelmi's logarithmic law, the amounts of sugar or 

 ester hydrolysed can be represented by the following equations : 



where K is the reaction constant in the experiment when protein 

 is absent, and K' the constant when it is present, A is the original 

 amount of sugar or ester, and x and x the amounts hydrolysed in 

 the time /, in the presence and absence of protein respectively. 

 Then 



K log A - log (A - x) 

 K' log A - log (A - *')' 



If now d be the concentration of the acid when no protein is 

 present and Z be the effective concentration in the parallel experiment 

 with protein, then 



K'.d 



z = - ir . 



By subtracting Z, found thus, from the original concentration, the 

 amount of acid that had entered into combination with the known 

 amount of added protein can be readily determined. 



Cohnheim determined the combining powers of certain proteoses, 

 prepared by the methods of Kuhne and Chittenden, with the follow- 

 ing results (at 40 C.) : Prot-albumose in a concentration of 2^ per 

 cent, combines with 4*32 per cent, of its weight of hydrochloric acid 

 and in a concentration of 1*25 per cent, with only 3*5 per cent. ; in a 

 concentration of 5 per cent., however, it combines with as much as 

 4'9 per cent, of its weight of acid. Deutero-proteose combines with 

 5*48 per cent., hetero-albumose with S'i6 per cent, and antipeptone 

 with 15*87 per cent, of their weights of hydrochloric acid in 2\ per 

 cent, solutions at 40 C. 



With the exception of antipeptone, which is a strong base, the 

 proteoses investigated appear to combine with less hydrochloric acid 

 in diminished concentrations. This is due to the fact that in dilute 

 solutions a certain amount of hydrolysis occurs : 

 Alb. Cl + H 2 O = Alb, OH + HC1. 



