Distribution and Some Properties of Acid Phosphatase in the 7,12‐Dimethylbenz[a]anthraccne‐Induced Rat‐Mammary Carcinoma

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Abstract
Differential centrifugation and gel‐chromatography techniques have been employed to study the distribution and molecular forms of acid phosphatase in rat mammary tumours induced by 7,12‐dimethylbenz[a]anthracene. With p‐nitrophenylphosphate as substrate three distinct forms of acid phosphatase activity were separated on gel chromatography.Enzyme I (Mr > 200000) and enzyme II (Mr 120000) were found to have similar biochemical properties and differential centrifugation indicated that both enzymes are present in a sedimentable fraction. Disruption of a mitochondrial‐lysosomal fraction by freezing and thawing released 45% of the total acid phosphatase of the fraction into a soluble phase. Treatment with detergent solubilized the bound enzyme. The possibility of two forms of acid phosphatase, one bound and one freely soluble, in the lysosomes of the rat mammary tumour is discussed.Enzyme III (Mr 30000) is localized in the soluble fraction of the tumour cell and is biochemically distinct from enzymes I and II.The overall findings are examined in relation to the properties and distribution of acid phosphatase in other tissues.

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