Separation and recombination of the ethylene glycol bis (beta-aminoethyl ether)-N,N'-tetraacetic acid-sensitizing factor obtained from a low ionic strength extract of natural actomyosin.

The ethylene glycol bis(P-aminoethyl ether)-N, N’-tetraacetic acid-sensitizing factor extracted from natural actomyosin at low ionic strength was concentrated in the fraction obtained between 40 and 60% ammonium sulfate saturation. Fractionation within narrower salt limits and at low protein concentrations yielded a troponin-rich fraction at 40 to 53% saturation and a tropomyosin-rich fraction at 53 to 60% saturation. These ammonium sulfate fractions could be further purified by isoelectric precipitation at pH 4.6. The supernatant of the 40 to 53 % fraction was shown to contain primarily troponin, while the precipitate of the 53 to 60% fraction was pure tropomyosin. It was found that for maximal EGTAsensitizing factor activity a ratio of tropomyosin to troponin of 1: 1.3, w/w, was required. This combination appears to form a complex which sediments as a single peak in the ultracentrifuge with a sedimentation constant of 5.15 S.