DEPHOSPHORYLATION OF ADENOSINE TRIPHOSPHATE BY TISSUES OF THE AMERICAN COCKROACH, PERIPLANETA AMERICANA (L.)

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Abstract
1. The dephosphorylation of ATP by various tissues of the American cockroach was investigated. It was found that these tissues differ in their dephosphorylating activity and may be rated, in decreasing order, approximately as follows: muscle, fat body, Malpighian tubes, nerve cord, brain, hindgut, foregut and midgut. 2. In general, both Mg and Ca ions activated the breakdown of ATP, although Mg was more effective. The magnitude of activation by these bivalent cations depended on the tissue. 3. Some differences due to sex were found. The dephosphorylating activity of the muscle and hindgut of the female was significantly greater than that in the male either in the absence of bivalent cations or in the presence of Ca ions. The fat body of the male, in the presence of Mg ions, was more active than that of the female. 4. The dephosphorylation of ATP by roach muscle was inhibited by p-chloromercuribenzoate, but not by azide and fluoride. Since these three compounds were effective inhibitors of house fly flight muscle ATPase, this distinction further emphasizes the heterogeneity of ATP breakdown mechanisms in insects.