Isolation of intact chloroplasts with high CO2fixation capacity from sugarbeet leaves containing calcium oxalate
✍ Scribed by S. P. Robinson
- Book ID
- 104619598
- Publisher
- Springer
- Year
- 1983
- Tongue
- English
- Weight
- 341 KB
- Volume
- 4
- Category
- Article
- ISSN
- 0166-8595
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✦ Synopsis
Intact chloroplasts were isolated from sugarbeet leaves by the mechanical disruption technique normaUy used for spinach. The chloroplast pellet contained a ring of white irregularly shaped crystals which were identified as calcium oxalate. The chloroplasts were greater than 90% intact yet good rates of CO 2 fixation were only obtained when inorganic pyrophosphate or 3-phosphoglycerate were added to the assay medium. Chloroplasts free of calcium oxalate were prepared by purification on a three step Percoll gradient. These purified chloroplasts were highly intact and showed high rates of C0a fixation without adding inorganic pyrophosphate or 3-phosphoglycerate. With optimal assay conditions (0.2 mM orthophosphate and pH 8.0) rates of 110-130 ~ mole per milligram chlorophyll per hour were routinely obtained. It is concluded that intact chloroplasts capable of high rates of C% fixation can be prepared from sugarbeet leaves using a simple three step Percoll gradient.