70 
CHEMISTRY: T. B. JOHNSON 
TABLE I 
CARBON DIOXIDE 
PROTEIN 
By acid 
hydrolysis 
per cent 
By alkali 
hydrolysis 
per cent 
Egg albumin. . 
Serum globulin 
Parahamoglobin 
[0.352 
] 0.332 
[0.370. 
0.336 
2.09 
2.77 
2.41 
2.38 
0.680 
'4.63 
4.53 
Keratin 
Elastin. 
0.364 
0.372 
0.130 
( 
In the course of investigations now in progress in this laboratory, 
dealing with the study of new hydantoin and thiohydantoin combi- 
nations of biochemical interest, I had occasion to determine whether 
gaseous products are evolved by hydrolysis of pure fibroin and also 
casein. I now find that both these proteins break down on hydrolysis 
with sulphuric acid with evolution of carbon dioxide and obtained from 
casein 0.35% of its weight in the form of this gas, while three quantita- 
tive experiments with fibroin gave the values 0.20, 0.27, and 0.25% 
respectively. When boiling 30% barium hydroxide solution was used 
for the hydrolysis of fibroin (the action of barium hydroxide on casein is 
being investigated), we obtained the values 1.08 and 1.05% of carbon 
dioxide. In other words, in the cases of the two proteins elastin and 
fibroin about five times as much carbon dioxide is produced by alkaline 
hydrolysis as is obtained by digestion with sulphuric acid. By inspection 
of Table I it will be seen that the greatest increase was obtained by 
hydrolysis of keratin. The results obtained with fibroin have special 
significance because the production of carbon dioxide in this case does 
not result from the breaking down of cystin, as this protein is free from 
sulphur. 
The marked difference in behavior towards acids and alkalis and the 
further fact that the quantity of carbon dioxide formed by hydrolysis 
is not proportional to the amount of arginine present in the respective 
proteins, suggest that urea combinations are the precursors of this 
gaseous hydrolytic product. Carbon dioxide would be a normal prod- 
uct of hydrolysis of such groupings and their destruction would be more 
easily accomplished by the action of alkalis than with acids. Lippich 
has advanced the idea that uramido acids, of which hydantoic acid II 
is the protot3^e, are the types of urea combinations which functionate 
in these changes. Such groupings, as is well known, are hydrolyzed by 
alkalis with formation of a-amino acids, carbon dioxide and ammoma. 
