CHOLINE KINASE OF RAPESEED (BRASSIGA CAMPESTRIS L.)

Abstract

Choline kinase from aqueous extracts of Polish rapeseed (Brassica campestris L.) has been purified 25-fold by fractionation with acetone and calcium phosphate gel. The purified enzyme was relatively stable when stored frozen at neutral pH, and was active over a broad range of pH, the optimum being at about pH 8.6 – 10.0. The enzyme required Mg++ and exhibited maximum activity only when the Mg++: ATP ratio was 1:1. Phosphorylcholine, ADP, and Mn++ inhibited the activity. In addition to choline, the enzyme preparation phosphorylated dimethyl- and diethyl-aminoethanol but not ethanolamine. The choline kinase from rapeseed is similar to that from yeast except that the former does not require sulphydryl groups for activation.