[Isolation of two forms of DNA polymerase alpha from roe of loach. Physico-chemical properties of the isoenzymes].

The procedures of isolation and purification of DNA polymerase alpha from mature eggs of the teleost fish Misgurnus fossilis (loach) are described. The two forms of DNA polymerase alpha were separated by chromatography on hydroxylapatite. The physical properties of the purified isoenzymes alpha 1 and alpha 2 were studied. Both forms of alpha-polymerase had the same values of the Stokes radius (63 A) and sedimentation coefficients (6.8 S). Gel filtration and sedimentation analyses revealed that the calculated values of molecular weight (M) and friction ratio (f/fo) for the isoenzymes are equal to 170 000 (M) and 1.72 (f/fo), respectively. The isoelectric point is equal to 5.7 for alpha 1-polymerase and 5.8 for alpha 2-polymerase after isoelectric focusing of the enzymes in polyacrylamide gels. It is concluded that DNA polymerase alpha from loach eggs is represented by two species of the acidic high molecular weight proteins with a prominent spatial asymmetry.