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The presence of an ATP-ase in water extracts from uterine and heart muscle was demonstrated. A method is described for determination of ATP-ase activity of actomyosin and other extracts. It is a sensitive biological test to determine small amounts of ATP. The two ATP-ases prepared from cross-striated, heart and uterine muscle show different activity. Both ATP-ases show the greatest activity in the case of cross-striated muscle extracts and the lowest value in the uterine-extract (per unit wet weight of muscle). The character of recombination is different in the actomyosin extracts prepared from the three muscle types. The ATP-ase activity of uterine actomyosin extract increases with precipitation by dilution and by addition of Ca++ ions, while with addition of Mg++ the activity decreases.
A.I. Csapo (Thu,) studied this question.