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PROTEINS OF THE MUSCLES. 569
by saturating the filtrate with the salt. It is similar to serglobulin, but coagu-
lates at 63° C. (Halliburton). MyoaUmmin, or muscle-albumin, seems to
be identical with seralbumin (seralbumin a, according to Hallibi bton), and
probably originates only from the blood or the lymph. Proteoses and peptones
do not seem to exist in the fresh muscles.
Alter the complete removal from the muscle of all protein bodies which are
soluble in water and ammonium chloride, an insoluble protein remains which
only swells in ammonium-chloride solution, and which forms with the other insoluble
constituents of the muscular fiber the " muscle-stroma." According to Danilew-
sky the amount of such stroma substance is connected with the muscle activity.
He maintains that the muscles contain a greater amount of this substance, com-
pared with the myosin present, when the muscles are quickly contracted and
relaxed, the correctness of which report has recently been disputed by Saxl. 1
According to J. Holmgren, 2
this stroma substance does not belong to either
the Qucleoalbumin or the nucleoprotein group. It is not a glucoproteid, as it
does not yield a reducing substance when boiled with dilute mineral acids. It is
very similar to the coagulable proteins, and dissolves in dilute alkalies, forming
an albuminate. The elementary composition of this substance is almost the same
as that of myosin. There is no doubt that the insjluble substances, myofiorin
and myosin fibrin, which are formed, according to v. Fukth, in the coagulation of
the plasma, also occur among the stroma substances. When the muscles are
previously extracted with water, the stroma substances also contain a part of the
myosin hereby made insoluble. The observations of Saxl on rabbits’ muscles
agree with this view that the fresh muscle after work contains 11.5-21.6 per cent
of the total protein in an insoluble form, while the muscle after rigor mortis con-
tains on the contrary 71.5-73.2 per cent.
To the proteins insoluble in water, and neutral salts, belongs the
nucleoprotein detected by Pekelharing, which occurs as traces and is
soluble in faintly alkaline water, and which probably originates from
the muscle nuclei. According to Bottazzi and Ducceschi 3
the heart
muscle is richer in nucleoprotein than the skeletal muscle.
Muscle-syntonin, which may be obtained by extracting the muscles with
hydrochloric acid of 1 p.m., and which, according to K. Morner, is less soluble
and has a greater aptitude to precipitate than other acid albumins, seems not
to occur preformed in the muscles. Heubner’s 4
mytolin is modified muscle-
proteid, chiefly myosin, which has lost a part of its sulphur by the action of alkali.
Proteins of the Muscle-plasma. As above stated, myosin was ordi-
narily considered as the coagulated modification of a soluble protein
existing in the muscle-plasma. As in blood-plasma there is present
a mother-substance of fibrin, fibrinogen, so also there exists in the
muscle-plasma a mother-substance of myosin, a soluble myosin or a
myosinogen. This body has not thus far been isolated with certainty.
1
Hofmeister’s Breitage, 9.
2
See footnote 1, p. 566.
3
Pekelharing, Zeitschr. f. physiol. Chem., 22; Bottazzi and Ducceschi, Centraibl.
f. Physiol., 12.
4
Arch. f. exp. Pathol, u. Pharm., 53.
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