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Dihydroxyacetone phosphate reductase in plants.
R W Gee1, R U Byerrum, D W Gerber
1Michigan State University, Department of Biochemistry, East Lansing, Michigan 48824.
Plant Physiology
|January 1, 1988
Summary
Two forms of dihydroxyacetone phosphate reductase exist in plants, with one primarily in chloroplasts and the other in the cytosol. The chloroplast form
Area of Science:
- Plant biochemistry
- Enzymology
Background:
- Dihydroxyacetone phosphate reductase (DHPR) plays a crucial role in plant metabolism.
- Understanding the different forms and locations of DHPR is essential for elucidating its function.
Purpose of the Study:
- To identify and characterize the different forms of dihydroxyacetone phosphate reductase in plants.
- To determine the subcellular localization and differential regulation of DHPR forms.
Main Methods:
- Development of an improved homogenizing medium for enzyme activity measurement.
- Enzyme purification and separation using dialysis, ammonium sulfate precipitation, DEAE cellulose, and Sephacryl S-200 chromatography.
- Subcellular fractionation and analysis of enzyme activity in chloroplasts and cytosol.
Main Results:
- Two distinct forms of DHPR were identified in spinach, soybean, pea, and corn leaves.
- Approximately 80% of DHPR activity was localized in the chloroplast, with the remaining 20% in the cytosol.
- The chloroplast DHPR form exhibited significantly higher specific activity and was stimulated by dithiothreitol and thioredoxin, unlike the cytosolic form.
Conclusions:
- Plants possess distinct chloroplast and cytosolic forms of dihydroxyacetone phosphate reductase.
- The chloroplast DHPR form is likely involved in photosynthetic carbon metabolism and is regulated by redox conditions via thioredoxin.
- Further research into DHPR regulation can provide insights into plant metabolic efficiency.