THERMAL-DENATURATION OF BETA-CONNECTIN ISOLATED FROM CARP MUSCLE

beta-Connectin, a 2,100 kDa fragment of connectin, was extracted with 0.1 M phosphate buffer at pH 6.6 and purified on a Bio-Gel A 50 m gel filtration from carp skeletal myofibrils. The isolated connectin was i n the native state judging from the fact that it enhanced aggregation of both myosin and actin filaments and appreciably elevated actomyosin Mg-ATPase activity. The thermal denaturation of connectin was measure d in 0.1 M and 0.6 M KCl solutions of neutral pH by means of turbidity . Increase in turbidity was observed at 40 degrees C and occurred mark edly above 50 degrees C. A physiological concentration of Ca2+ and Mg2 + did not affect turbidity. The loss of interaction of connectin with myosin was caused by the denaturation of myosin at lower temperatures rather than that of connectin.