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Published on: May 29, 2016
Lactate dehydrogenases in cyanobacteria
Archives of Microbiology
|June 20, 1975
Summary
This study investigates NAD-linked D-lactate dehydrogenase in cyanobacteria. The enzyme is crucial for D-lactate metabolism, with its activity varying with culture age.
Area of Science:
- Biochemistry
- Microbiology
- Photosynthesis
Background:
- Unicellular cyanobacteria possess NAD-linked lactate dehydrogenases for D- and L-lactate.
- Understanding these enzymes is key to cyanobacterial metabolic pathways.
Purpose of the Study:
- To partially purify and characterize NAD-linked D-lactate dehydrogenase from Synechococcus 6716.
- To investigate the physiological roles of D-lactate dehydrogenase in cyanobacterial metabolism.
Main Methods:
- Partial purification of D-lactate dehydrogenase.
- Enzyme property analysis (molecular weight, specificity, inhibition).
- Metabolic studies using radiolabeled D-lactate and glucose, and analysis of end products.
Main Results:
- The D-lactate dehydrogenase (ca. 115-120 kDa) is specific, autooxidizable, and inhibited by iodoacetamide, oxamate, and ATP.
- D-lactate carbon incorporated into cell material during photosynthesis; lactate not a sole carbon source.
- Aerobic oxidation of D-lactate and pyruvate in the dark, with acetate excretion. D-lactate detected in endogenous metabolism.
- Enzymes for lactate production from glucose/glycogen present, but activity declines in older cultures.
Conclusions:
- D-lactate dehydrogenase plays a role in cyanobacterial carbon metabolism, particularly during active growth.
- Enzyme activity is regulated by culture age, suggesting metabolic shifts in cyanobacteria.
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