Date of Award


Document Type


Degree Name

Master of Science




Epidermal Ca++-activated ATPase was investigated in relation to the molt cycle of the blue crab, Callinectes sapidus. Premolt and postmolt tissue samples demonstrated significant elevations in Ca++-activated ATPase activity in comparison to intermolt tissue samples. These results support the suggestion that this enzyme may participate in demineralization of the old cuticle, as well as calcification of the new cuticle.

The enzyme is localized in the heavy particulate-nuclear fraction and is distinguished from mitochondrial Ca++ ATPase found in other tissues by differences in sensitivity to mersalyl acid. 0 The enzyme is most active at 49 C and has highest activity at pH values near 6.0. Reaction of the Ca++ ATPase with its substrate ATP produces a Vmax of 17.3 nmoles Pi mg-1 protein minute-1 in intermolt crabs. The Km value for ATP is 3.61 x 10-4M and the Q10 is 2.48.

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