LACTALBUMIN. ENZYMES. 653 



MANN found that it crystallizes in forms similar to ser- or ovalbumin. 

 It coagulates, depending on the concentration and the amount of salt 

 in solution, at 72-84 C. It is similar to seralbumin, but differs from 

 it in having a considerably lower specific rotatory power: (a)p = 37. 

 According to FASAL 1 it is especially rich in tryptophane, namely, 3.07 

 per cent. 



The principle of the preparation of lactalbumin is the same as for the 

 preparation of seralbumin from serum. The casein and the globulin 

 are removed by MgS04 in substance, and the filtrate treated as previously 

 stated (page 263). 



The occurrence of other proteins, such as proteases and peptones, in milk has 

 not been positively proved. These bodies are easily produced as laboratory 

 products from the other proteins of the milk. Such a laboratory product is 

 MILLON'S and COMAILLE'S lactoprotein, which is a mixture of a little casein with 

 changed albumin, and proteose 2 which is formed by chemical action. In regard 

 to opalisin, see Human Milk, p. 662. 



Milk also contains, SIEGFRIED 3 claims, a nucleon related to phos- 

 phocarnic acid, which yields fermentation lactic acid (instead of para- 

 lactic acid) and a special carnic acid, orylic acid (instead of muscle carnic 

 acid), as cleavage products. Lactophosphocarnic acid may be precipitated 

 as an iron compound from the milk freed from casein and coagulable 

 proteins as well as from earthy phosphates. 



Milk also contains enzymes of various kinds. Of these we must men- 

 tion catalases, peroxidases, and redudases, but the statements as to their 

 occurrence in the milk from different animals as well as the question 

 how much of their action is due to micro-organisms are conflicting. 

 Among these enzyme actions a special interest has been given to the 

 SCHARDINGER reaction, which consists in the fact that milk at 70 C. 

 in the presence of formaldehyde or acetaldehyde reduces certain dyes, 

 such as methylene blue, to leucobases. An amylolytic enzyme which 

 converts starch into maltose occurs, especially, in human milk, while 

 it is absent in cow's milk or occurs only to a slight extent. A fermenta- 

 tion enzyme which in the absence of micro-organisms decomposes the 

 lactose into lactic acid, alcohol, and C02, occurs, according to STOKLASA 4 

 and his co-workers, in cow's milk as well as in human milk. Human 

 milk, as well as cow's milk, contains a lipase which has the property 

 at least of acting upon monobutyrin. BABCOCK and RUSSEL have 

 found in these two kinds of milk, as well as certain others, a proteolytic 



1 Sebelien, Zeitschr., f. physiol. Chem., 9; Wichmann, ibid., 27; Fasal,- Bioch. 

 Zeitschr., 44. 



8 See Hammarsten, Maly's Jahresber., 6, 13. 

 8 Zeitschr. f. physiol. Chem., 21 and 22. 

 4 See Chem. Centralbl., 1905, 1, 107. 



