M.S. (Master of Science)
Department of Chemistry
Adenosine triphosphatase||Enzyme activation||Enzyme inhibitors
The ATPase activity of submitochondrial particles, chloroform- released ATPase, and F₁-ATPase prepared from beef heart mitochondria, was studied as a function of ATP concentration and temperature in the presence and absence of selected inhibitors and activators. It was shown that the double reciprocal plots of ATPase activity versus ATP concentration are linear for submitochondrial particles and the chloroform-released ATPase, but is curved for F₁-ATPase. The ATPase activity of all three preparations is inhibited in a similar manner by tetracaine, a local anesthetic, and is activated by bicarbonate. Tetracaine does not eliminate the curvature of the F₁-ATPase reciprocal plot, but bicarbonate does. Tetracaine was also shown to inhibit ATPase activity in the presence of bicarbonate. The temperature dependence of ATPase activity was studied by one of two methods: by using Tris buffers for which the pH was adjusted to 7.5 at each temperature, or using a single Tris buffer, adjusted to a pH of 7.5 at room temperature, for all temperatures. It was shown that the temperature dependence of chloroform-released ATPase and F₁-ATPase are similar, using either method. The Arrhenius plots reveal a steep increase in activity with temperature between 2.5°C and 18°C; a region of nearly constant activity between 18°C and 40°C; and another increase in activity above 40°C. Chloroquine, an antimalarial drug, was shown to cause partial inhibition of the ATPase activity of submitochondrial particles and chloroform-released ATPase, with half maximal inhibition being given by 0.75 mM and 0.60 mM chloroquine, respectively.
O'Brien, Kevin L., "Comparison of F₁-ATPase and chloroform-released ATPase : dependence of activity on temperature, substrate concentration, and inhibitors" (1987). Graduate Research Theses & Dissertations. 1867.
ix, 122 pages
Northern Illinois University
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