In recent years, many investigators have made various studies on the chemical and physicochemical properties of myosin extracted from fish muscle. Its behavior is still, however, very inadequately known. The author isolated the myosin from finely chopped fresh muscle of carp-fish by the use of potassium chloride (about 1 N) as an extracting medium, with the addition of potassium hydrophosphate to buffer the solution.
The myosin, purified by the precipitation by increase or decrease ?? of salt concentration, is a viscous liquid with opaline color.
1) The isoelectric point of the salt-free precipitated protein, measured by the method of electrophoresis under the microscope, was at pH 5.1 to 5.2 (Table 1); and the point of minimum acid and base-binding, measured by the method of Salter's (21) and Edsall's (6), was at pH 6.1 to 6.2.
2) The myosin remained insoluble in pure water or potassium chloride solution of very low concentration. At pH 7.2 it first became appreciable soluble in a quater normal salt solution, but almost soluble in a half normal salt solution. One to two normality of salt solution was the most adequate concentration for the solvent (Table 2). There was generally, however, large amounts of insoluble residue of myosin at pH 5.6 to acid side (Table 3).
3) The minimal percentage of ammonium sulfate required for salting out was 21.4 to 22.6 at pH 7.4 (Table 4).
4) The viscosity of this protein was of a higher order of magnitude than that of Wyman's muscle globulin or of Weber's myogen (Fig. 1).
Some physicochemical properties of the myosin isolated from fresh muscle of carp-fish here studied were almost identical with those of mammals, and to this protein gave the author the same name as v. Fürth's myosin,