ADENOSINE TRIPHOSPHATASE IN THE MITOTIC APPARATUS

Abstract

The idea that "working" molecules have the properties of ATPases has been a central theme in the study of the biochemistry of motility, even though no concensus exists even in the field of muscle biochemistry as to the role of ATP or of the splitting of ATP. In the present study, the existence of a highly specific ATPase in the mitotic apparatus has been demonstrated. This activity is confined to the splitting off of the terminal phosphate of adenosine triphosphate; GTP, CTP, and UPT are not substrates for it. The presence of the enzyme in the mitotic apparatus allows the hypothesis that ATP is concerned with the mechanochemical transduction by which the chromosomes are moved. The evidence favors the conclusion that the ATPase activity is associated with the fibrous structural components of the mitotic apparatus; it becomes soluble when the apparatus is dispersed in 0.53 M KC1 and remains in stable association with the structure when it is stabilized by Mg++ ions. This conclusion can be verified only by a satisfactory isolation of the molecules responsible for the fibrous structure.