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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) D =—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 MgSC>4 in substance, and the filtrate treated as previously
stated (page 263).
The occurrence of other proteins, such as proteoses 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
Millox’s and Comatlle’s lactoprotein, which is a mixture of a little casein with
changed albumin, and proteose * which is formed by chemical action. In regard
to opalisin, see Human Milk, p. G62.
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 reductases, 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 decompose^ the
lactose into lactic acid, alcohol, and CO2, 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
^ebelien, Zeitschr., f. physiol. Chem., 9; Wichmann, ibid., 27; Fasal, Bioch.
Zeitschr., 44.
* See Hammarsten, Mary’s Jahresber., 6, 13.
8
Zeitschr. f. physiol. Chem., 21 and 22.
See Chem. Centralbl., 1905, 1, 107.
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