Mixed function oxidases from germinating castor bean endosperm |
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Authors: | Owen Young Harry Beevers |
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Affiliation: | Thimann Laboratories, University of California, Santa Cruz, CA 95064, U.S.A. |
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Abstract: | Homogenates from germinating castor bean endosperm were fractionated by sucrose density gradient centrifugation and examined for mixed function oxidase activity. Activity of cinnamic acid 4-hydroxylase and p-chloro-N-methylaniline N-demethylase was highest in the endoplasmic reticulum fraction. Activity of both enzymes is dependent on NADPH and on molecular oxygen; both activities are inhibited by carbon monoxide. When challenged with a number of potential inhibitors the enzymes responded in ways fairly typical of mixed function oxidases from other plants and animals. The N-demethylase appears to be specific for N-methylarylamines. In the absence of NADPH, cumene hydroperoxide is able to support N-demethylation. The mechanistic significance of this activity is discussed. |
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Keywords: | Euphorbiaceae castor bean endoplasmic reticulum mixed function oxidase cinnamic acid 4-hydroxylase N-demethylase. |
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