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570 MUSCLES
Halliburton, who has detected in the muscles an enzyme-like substance,
11
myosin ferment," which is related to fibrin ferment but is not identical with it,
has also found that a solution of purified myosin, in dilute salt solution (5 per
cent MgS04 ), and sufficiently diluted with water, coagulates after a certain
time, and at the same time becomes acid, and a typical myosin-clot separates.
This coagulation, which is accelerated by warming or by the addition of myosin
’
ferment, is, according to Halliburton, a process analogous to the coagulation
of the muscle-plasma. According to this same investigator, myosin when dis-
solved in water by the aid of a neutral salt is reconverted into nvyosinogen, while
after diluting with water myosin is again produced from the nvyosinogen. The
musculin (paramyosinogen) is carried down, according to Halliburton, with the
myosin-clot, but has nothing to do with the coagulation, as the myosin-clot also
forms in the absence of musculin, and this last is not changed into myosin.
Besides the traces of globulin and albumin, which perhaps do not
belong to the muscle-plasma, there occur in mammals, according to
v. Furth, two proteins, namely, musculin (myosin according to v. Furth)
and myogen.
Musculin (Nasse) = paramyosinogen (Halliburton) = myosin (v.
Furth) forms about 20 per cent of the total proteins of the muscle-
plasma of rabbits. Its properties have already been given, and it is
sufficient to remark that its solutions beccme cloudy on standing, and
a precipitate of myosin fibrin occurs, which is insoluble in salt solutions.
Myogen, or myosinogen (Halliburton), forms the chief mass,
75-80 per cent, of the proteins of rabbit muscle-plasma. It does not
separate from its solutions on dialysis and is not a true globulin, but
a protein sui generis. It coagulates at 55-65° C. and is precipitated
in the presence of 26-40 per cent ammonium sulphate. Myogen solu-
tions are precipitated by acetic acid only in the presence of some salt.
It is converted into an albuminate by alkalies, this albuminate being
precipitable by ammonium chloride. Myogen passes spontaneously,
especially with higher temperatures as well as in the presence of salt,
into an insoluble modification, myogen fibrin. A protein, coagulating
at 30-40° C, soluble myogen fibrin, is produced as a soluble intermediate
step. This substance occurs to a considerable extent in native frog-
muscle plasma. It does not always occur in the muscle-plasma of
warm-blooded animals, and when it does it is present only to a slight
extent. It can be separated by precipitating with salt or by diffusion.
Halliburton’s assumption as to the action of a special myosin ferment
has not sufficient basis, according to v. Furth, nor has the often-admitted
analogy with the coagulation of the blood. The difference between
the musculin and the myogen in their becoming insoluble is that the
musculin passes into myosin fibrin without any soluble intermediate
Step-.
Myogen may be prepared, according to v. Furth, by heating, for a
short time, the dialyzed and filtered plasma to 52° C., separating it in
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