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 x 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. Only a very slow hydrolysis of phosphorylcholine by similar plant extracts was observed. This phosphatase activity was purified 200- or 300-fold and appeared to be caused by a nonspecific acid phosphatase. The activity of both the kinase and the phosphatase did not seem sufficient to account for the rapid equilibration of the large phosphorylcholine reservoir of plants with exogenous P(32)-labeled orthophosphate.

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Choline Kinase and Phosphorylcholine Phosphatase in Plants <sup><a href="#fn1" rid="fn1" class=" fn">1</a></sup>

K Tanaka

N Tolbert

A Gohlke

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 × 10m. 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.

Only a very slow hydrolysis of phosphorylcholine by similar plant extracts was observed. This phosphatase activity was purified 200- or 300-fold and appeared to be caused by a nonspecific acid phosphatase.

The activity of both the kinase and the phosphatase did not seem sufficient to account for the rapid equilibration of the large phosphorylcholine reservoir of plants with exogenous P^{-labeled orthophosphate.}

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Selected References

These references are in PubMed. This may not be the complete list of references from this article.

HERS HG. La fructokinase du foie. Biochim Biophys Acta. 1952 Apr;8(4):416–423. [PubMed] [Google Scholar]
Tolbert NE, Wiebe H. Phosphorus and Sulfur Compounds in Plant Xylem Sap. Plant Physiol. 1955 Nov;30(6):499–504.[PMC free article] [PubMed] [Google Scholar]
WITTENBERG J, KORNBERG A. Choline phosphokinase. J Biol Chem. 1953 May;202(1):431–444. [PubMed] [Google Scholar]

Department of Biochemistry, Michigan State University, East Lansing, Michigan

^{Present address: Sankyo Company, Limited, 2-58, 1-chome, Hiramachi, Shinagawa-ku, Tokyo, Japan.}

^{Present address: High Plains Research Foundation, Post Office Box 1267, Plainview, Texas.}

^{This investigation was supported by Public Health Service Research grant AM 05059. It has been approved for publication as journal article No. 3671 of the Michigan Agricultural Experiment Station.}

Copyright notice

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 × 10m. 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.

Only a very slow hydrolysis of phosphorylcholine by similar plant extracts was observed. This phosphatase activity was purified 200- or 300-fold and appeared to be caused by a nonspecific acid phosphatase.

The activity of both the kinase and the phosphatase did not seem sufficient to account for the rapid equilibration of the large phosphorylcholine reservoir of plants with exogenous P^{-labeled orthophosphate.}

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