Fractionation of the photochemical systems of photosynthesis. II. Cytochrome and carotenoid contents of particles isolated from spinach chloroplasts
| Autor: | N.K. Boardman, Jan M. Anderson |
|---|---|
| Rok vydání: | 1967 |
| Předmět: |
Chlorophyll
Chloroplasts Cytochrome Photosystem II Biophysics Centrifugation macromolecular substances Photosystem I Photochemistry Biochemistry Cytochrome C1 Glycosides Cytochrome f biology Cytochrome b Cytochrome b6f complex Cytochrome c Temperature food and beverages Cell Biology Carotenoids Spectrophotometry biology.protein Cytochromes Plants Edible Oxidation-Reduction |
| Zdroj: | Biochimica et Biophysica Acta (BBA) - Bioenergetics. 143:187-203 |
| ISSN: | 0005-2728 |
| DOI: | 10.1016/0005-2728(67)90120-x |
| Popis: | 1. Spinach chloroplasts were fragmented by incubation with digitonin, and the resulting particles examined for their cytochrome and carotenoid contents. Cytochrome difference spectra were recorded both at 20°C and 77°K, usually without prior extraction of the chlorophylls. 2. It is concluded that at least three cytochromes are localized in the chloroplast; cytochromes f and b 6 with α bands at 554 and 563 mμ respectively, and another cytochrome with an α band at about 559 mμ at 20°C and 557 mμ at 77°K. The cytochromes are present in the approximate molar ratio of 1:2:2, respectively. It is assumed tentatively that cytochrome 559 (chloroplasts) is a b -type cytochrome. The chloroplast contains 430 molecules of chlorophyll per molecule of cytochrome f and 118 molecules of chlorophyll per molecule of cytochrome b (cytochrome b 6 plus cytochrome 559). 3. The results presented for the particles prepared by digitonin treatment of chloroplasts show that cytochromes f and b 6 are associated with Photosystem 1 and cytochrome 559 with Photosystem 2. Cytochromes f and b 6 are partly solubilized from the Photosystem 1 particle by the digitonin, and the method of preparation of the particles was modified to minimize this loss. Cytochrome 559 appears to be tightly bound to the Photosystem 2 particle. 4. The four major carotenoids, β-carotene, lutein, violaxanthin and neoxanthin were found to be present in both types of particles, but in varying proportions. The particles representative of Photosystem 1 were enriched in β-carotene. |
| Databáze: | OpenAIRE |
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