Choline Kinase and Phosphorylcholine Phosphatase in Plants

Abstract

Choline kinase was present in barley and wheat roots and leaves of barley, wheat, tobacco, spinach and squash plants. The kinase was purified 25-fold from spinach leaves. The enzyme had a broad pH optimum between 7.5 and 10.0. Mg⁺⁺ was required for activity and in the presence of Mg⁺⁺ the enzyme was relatively stable. Maximum enzyme activity was obtained when the Mg⁺⁺: ATP ratio was 1:1. The K_m was 1 × 10⁻⁴ m. The kinase from leaves was similar to that from rapeseed or from yeast, except that the leaf and seed enzymes were not inhibited by compounds which attach sulfhydryl groups.