Full resolution (JPEG) - On this page / på denna sida - X. The Muscles - Proteins of the Muscles
<< prev. page << föreg. sida << >> nästa sida >> next page >>
Below is the raw OCR text
from the above scanned image.
Do you see an error? Proofread the page now!
Här nedan syns maskintolkade texten från faksimilbilden ovan.
Ser du något fel? Korrekturläs sidan nu!
This page has never been proofread. / Denna sida har aldrig korrekturlästs.
568 MUSCLES.
albuminates by dilute acids or alkalies. It is completely precipitated
upon saturation with NaCl, also by MgSO-i, in a solution containing
94 per cent of the salt with its water of crystallization (Halliburton).
The precipitated myosin readily becomes insoluble. Like fibrinogen it
coagulates at 56° C. in a solution containing common salt, but differs
irom it, since under no circumstances can it be converted into fibrin.
The coagulation temperature, according to Chittenden and Cummins,
not only varies for myosins of different origin, but also for the same
myosin in different salt solutions.
Myosin may be prepared in the following way, as suggested by Halli-
burton: The muscle is first extracted by a 5-per cent magensium-
sulphate solution, and by fractional precipitation with magnesium sul-
phate the musculin and then the myosin are precipitated (see Halli-
burton, 1. c).
The older and perhaps the usual method of preparation consists,
according to Danilewsky, 1
in extracting the muscle with a 5-10 per cent
ammonium-chloride solution, precipitating the myosin from the filtrate
by strongly diluting with water, and redissolving the precipitate in ammo-
nium-chloride solution, and the myosin obtained from this solution is
reprecipitated either by diluting with water or by removing the salt
by dialysis.
Musculin,2
called paramyosinogen by Halliburton, and myosin
by v. Furth, is a globulin which is characterized by its low coagulation
temperature, in frogs below 40°, in mammalia 42-48°, and in birds about
51° C, and which may vary in different species of animals. It is more
easily precipitated than myosin by NaCl or MgSC>4 (50 per cent salt,
including water of crystallization). According to v. Furth it is precipi-
tated by ammonium sulphate with a concentration of 12-24 per cent
salt. If the dead muscle is extracted with water a part of the musculin
goes into solution, and may be precipitated therefrom by carefully
acidifying. It separates from a dilute salt solution on dialysis. Mus-
culin readily passes into an insoluble modification which v. Furth calls
myosin fibrin. Musculin is called myosin by v. Furth, as he considers
it nothing but myosin. As musculin has a lower coagulation temper-
ature and has other precipitating properties for neutral salts than the
older substance called myosin, it is difficult to accept this view.
Myoglobulin. After the separation of the musculin and the myosin from the
salt extract of the muscle by means of MgSO-i, the myoglobulin may be precipitated
1
Zeitschr. f. physiol. Chem., 5, 158.
2
As we have up to the present no conclusive basis for the identity of the globulins
railed myosin and paramyosinogen, and also as the use of the name myosin for the
last-mentioned substance may readily cause confusion, the author does not feel
kistified in dropping the old name musculin (Nasse).
<< prev. page << föreg. sida << >> nästa sida >> next page >>
