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Localisation and characterization of the fatty acid synthesizing system in cells of Glycine max (soubean) suspension cultures.

Authors
Type
Published Article
Journal
Biochimica et Biophysica Acta
0006-3002
Publisher
Elsevier
Publication Date
Volume
489
Issue
3
Pages
370–380
Identifiers
PMID: 563244
Source
Medline
License
Unknown

Abstract

In course of a study of fatty acid synthetase in higher plants, non-green cell suspension cultures of Glycine max (soybean) served as model tissues. For the first time, a fatty acid synthesizing system was characterized in cell cultures of higher plants and was found to be solely located in proplastids of the cells. Optimum activity of the fatty acid synthesizing system in proplastids was observed between pH 8.0 and 8.2; with [1-14C]acetate as substrate, cofactors required were CoA, ATP, Mn2+, Mg2+, HCO3-, NADH and NADPH. The system was more sensitive towards NADH than NADHP. [1-14C]Acetate,[2-14C]-malonate and [3-14C]pyruvate served as precursors for fatty acids, indicating the presence of pyruvate dehydrogenase activity in proplastids. In disrupted proplastids, [2-14C]malonylCoA was a better precursor than [1-14C]acetylCoA. After incubation of proplastids with [2-14C]malonate, a small shift, from palmitic acid to higher homologs, of label incorporated was observed, as compared to incorporation of label from [1-14C]acetate and [3-14C]pyruvate. Under the conditions of the experiment, only small amounts of polyunsaturated fatty acids, the main fatty acid components of this organelle, were synthesized. In respect to fatty acid synthesis, the non-green cell suspension culture resembles photosynthetic leaf tissue.

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