Pyruvate dehydrogenase complex from germinating castor bean endosperm
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Updated: Aug 8, 2026

Preparation of Intact Tissue for Microscopic Analysis of the Endosperm Cell Layer in Developing and Mature Arabidopsis Seeds
Published on: May 16, 2025
1Department of Biochemistry, University of Missouri, Columbia, Missouri 65211.
Abstract:
Subcellular organelles from castor bean (Ricinus communis) endosperm were isolated on discontinuous sucrose gradients from germinating seeds which were 1 to 7 days postimbibition. Marker enzyme activities of the organelles were measured (fumarase, catalase, and triose phosphate isomerase) and the homogeneity of the organelle fractions was examined by electron microscopy. Pyruvate dehydrogenase complex activity was measured only in the mitochondrial fraction and attempts to activate or release the enzyme from the proplastid were not successful. A pathway is proposed for the most efficient use of endosperm carbon for de novo fatty acid biosynthesis that does not require the presence of the pyruvate dehydrogenase complex in the proplastid to provide acetyl-coenzymeA.
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