248 Some New Constituents of Milk. III 
Amino-Acids per 100 Gm. of Milk Protein. 
Alcohol-soluble protein. Casein. 
gm. gm. 
ATQinine Meee | okie 2: 92 ee 3.81 
Histidine sere ts co ce. ae 2.28 2.50 
EySInC Wee oh ea secs sae 3.98 9.95 
Ey Tositre Meme yp so coke 2.47 4.50 
These results show that casein yields much more basic nitrogen, 
as well as more arginine, histidine, or lysine, than does the alco- 
hol-soluble milk protein and demonstrate that these proteins are 
distinctly different in structure. 
The alcohol-soluble protein of milk does not yield more amide 
nitrogen, nor less basic nitrogen, or lysine, than do most other 
proteins, and in these respects does not resemble the alcohol- 
soluble proteins of vegetable origin, although so like wheat 
gliadin in its solubility in relatively strong alcohol. 
Further evidence that this peculiar protein has no genetic 
relation to casein is shown by the results of anaphylaxis experi- 
. ments made by Professor H. G. Wells with a preparation which 
we sent him, and also with a preparation of the casein from which 
the alcohol-soluble protein had been extracted by dilute alcohol. 
Sensitizing Dose. Intoxicating Dose. Result. 
gm. gm. 
Casein: rae: 0.001 Casein seston 0.05 Died in 15 min. 
Se Ca) See 0.001 oa igs a ee 0.05 Cale oem 
Alcohol-soluble Aleohol-sol- 
protein..... 0.001 uble protein 0.05 mena be) 
< 0.001 Gi 0.05 wee Miia hk yo % 
* 0.001 Casein. .<cce 0.05 No symptoms. 
fe 0.001 Rui ee 0.05 nS si 
Since acid compounds of the alcohol-soluble protein are soluble 
in water it is probable that a further quantity is present in the 
milk serum from which the casein had been precipitated. Ex- 
amination of the alcoholic extract of large quantities of the co- 
agulated protein obtained by boiling the acid filtrate from the 
casein failed to reveal the presence of any of this protein therein. 
On the other hand some was found in the filtrate from the 
coagulated proteins. Thus 20 liters of milk were made neutral, 
first to litmus and then to phenolphthalein, and the precipitates 
were successively filtered out. Such neutralization precipitates 
contain considerable protein, but numerous attempts have failed 
to detect the presence of the alcohol-soluble protein in them. 
