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- Title
Freezing of isolated thylakoid membranes in complex media. VIII. Differential cryoprotection by sucrose, proline and glycerol.
- Authors
Santarius, Kurt A.
- Abstract
The cryoprotective efficiency of sucrose, proline and glycerol for chtoroplast membranes isolated from spinach leaves (Spinacia oleracea L. cv. Monatol) was determined after freeze-thaw Ireatment in media containing the predominant inorganic electrolytes of the chloroplast stroma., In most cases, the protective capacity of equimolar concentrations of the cryoprotectants followed' the order sucrose> proline > glycerol. The lower the freezing temperature the less cryoprotectant was necessary for comparable preservation of the capacity of photosynthetic electron transport. Likewise, the cryoprotective efficiency of sucrose for cyclic photophosphorylation arid light-induced proton gradient increased with decreasing freezing temperature. In contrast, while proline effectively stabilized these membrane reactions at mild and moderate freezing temperatures, it was much less efficient at more severe freezing stress. Cryoprotection of photophosphorylation and proton gradient formation at given initial, concentrations of glycerol was largely independent of the freezing temperature. While dissociation of the peripheral part of chloroplast coupling factor (CF1) during freeze-thaw treatment cannot be prevented in the presence of lower initial concentrations of proline and glycerol and, at mild freezing temperatures., of sucrose, the latter may stabilize this protein complex at least under more severe freezing conditions. The differences in the cryoprotective efficiency of the solutes are discussed relative to their non-ideal activity-concentration profiles, solution properties and penetration behaviour across the thylakoid membrane.
- Subjects
THYLAKOIDS; SUCROSE; PROLINE; ELECTRON transport; PHOSPHORYLATION; SPINACIA
- Publication
Physiologia Plantarum, 1992, Vol 84, Issue 1, p87
- ISSN
0031-9317
- Publication type
Article
- DOI
10.1111/j.1399-3054.1992.tb08769.x