Acid phosphatase in the tail of Xenopus laevis during development and metamorphosis

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Abstract
Quantitative and qualitative changes in acid phosphatase during growth and metamorphosis of the tail of Xenopus laevis have been investigated. Enzyme activity was assayed by two methods using different substrates, p‐nitrophenyl phosphate and β‐glycerophosphate. The enzyme was found to be consistently more active with p‐nitrophenyl phosphate. Specific activity of whole tail homogenates assayed by both methods remains constant during development and early metamorphosis, and then rises sharply as the rate of tail regression begins to accelerate. Total phosphatase activity of whole tail homogenates rises linearly during development and early metamorphosis, and then maintains a high level during the first half of the period of tail regression. After this it declines. Regional localization of acid phosphatase activity has been determined in different parts of the tail: dorsal fin, ventral fin, and muscle. Changes in the apparent Km and pH optimum of acid phosphatase occur during tail regression. These properties remain constant during development and early metamorphosis, and are then found to change approximately in parallel with changes in enzyme activity during tail resorption. Possible implications of these biochemical events are discussed.