Document Detail

On the light dependence of Fatty Acid synthesis in spinach chloroplasts.
MedLine Citation:
PMID:  16663156     Owner:  NLM     Status:  PubMed-not-MEDLINE    
The capacity of intact chloroplasts to synthesize long chain fatty acids from acetate depends on the stroma pH in Spinacia oleracea, U. S. hybrid 424. The pH optimum is close to 8.5. Lowering of the stroma pH leads to a reduction of acetate incorporation but does not suffice to eliminate fatty acid synthesis completely. Chain elongation from palmitic to oleic acid shows the same pH dependence. Fatty acid synthesis is activated in the dark upon the simultaneous addition of dihydroxyacetone phosphate and orthophosphate supplying ATP and oxaloacetate for reoxidation of NADPH in the stroma. Under these conditions both dark fatty acid synthesis and synthesis of oleate from palmitate show the same pH dependence as in the light. Dark fatty acid synthesis is further stimulated by increasing the stromal Mg(2+) concentration with the ionophore A 23187. In contrast to CO(2) fixation, dark fatty acid synthesis is considerably reduced by dithiothreitol (DTT). This observation may be due to an acetyl-CoA deficiency, caused by a nonenzymic acylation of DTT, and a competition for ATP between DTT-activated CO(2) fixation and fatty acid synthesis. Because d,l-glyceraldehyde as inhibitor of CO(2) fixation compensates the DTT effect on dark fatty acid synthesis, reducing equivalents may be involved in the light dependence of acetate activation.
A Sauer; K P Heise
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Publication Detail:
Type:  Journal Article    
Journal Detail:
Title:  Plant physiology     Volume:  73     ISSN:  0032-0889     ISO Abbreviation:  Plant Physiol.     Publication Date:  1983 Sep 
Date Detail:
Created Date:  2010-06-29     Completed Date:  2010-06-29     Revised Date:  2010-09-14    
Medline Journal Info:
Nlm Unique ID:  0401224     Medline TA:  Plant Physiol     Country:  United States    
Other Details:
Languages:  eng     Pagination:  11-5     Citation Subset:  -    
Lehrstuhl für Biochemie der Pflanze, Universität Göttingen, Untere Karspüle 2, D-3400 Göttingen, Federal Republic of Germany.
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