Choline Kinase Activity in Castor Bean Endosperm
The reaction catalyzed by choline kinase (E.C. 18.104.22.168: AT: cholinephosphotransferase) is the first committed reaction of the nucleotide pathway for phosphatidylcholine (PtdCho) biosynthesis. Various theoretical considerations have led to the suggestion that this reaction is far from equilibrium and, along with the cytidylyltransferase reaction, may be rate-limiting for PtdCho biosynthesis in some animal tissues (1). As part of our studies on the regulation of PtdCho biosynthesis in plants we have investigated the properties of this enzyme and the in vivo concentrations of metabolites involved in the reaction in postgermination castor bean endosperm.
KeywordsTissue Water Content Choline Kinase Saturate Substrate Concentration Choline Incorporation Commit Reaction
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