THYLAKOIDS FROM PEA-SEEDLINGS GROWN UNDER INTERMITTENT LIGHT - BIOCHEMICAL AND FLASH-SPECTROPHOTOMETRIC PROPERTIES
Autor(en): | JAHNS, P JUNGE, W |
Stichwörter: | A/B-BINDING PROTEINS; ABSORPTION-CHANGE; Biochemistry & Molecular Biology; CHLOROPHYLL-B; ELECTRON-TRANSPORT; HIGHER-PLANTS; MEMBRANES; PHOTOSYNTHETIC WATER OXIDATION; PHOTOSYSTEM-II PREPARATION; PROTON-PUMPING ACTIVITY; SHORT-CIRCUIT | Erscheinungsdatum: | 1992 | Herausgeber: | AMER CHEMICAL SOC | Journal: | BIOCHEMISTRY | Volumen: | 31 | Ausgabe: | 32 | Startseite: | 7390 | Seitenende: | 7397 | Zusammenfassung: | Thylakoid membranes were isolated from pea seedlings grown under intermittent light (2-min light/118-min dark cycles). These preparations differed from controls (thylakoids from plants grown under 16-h light/8-h dark cycles) in the following respects: 15 times smaller chlorophyll/protein ratio, 10 times greater chlorophyll a/b ratio, absence of light-harvesting chlorophyll a/b binding proteins, and 2-3-fold greater ratio of photosystem II over photosystem I. In addition we found the following: (1) Electrogenic electron transfer around cytochrome b6/f under flashing light was greatly enhanced, probably as a consequence of the greater photosystem II/photosystem I ratio. (2) The rate of proton uptake from the medium at the acceptor side of photosystem II was enhanced, probably by unshielding of the quinone binding domain. (3) The N,N'-dicyclohexylcarbodiimide sensitivity of the proton-pumping activity of photosystem II was absent, which was consistent with the attribution of a N,N'-dicyclohexylcarbodiimide-induced protonic short circuit to chlorophyll a/b binding proteins. (4) The sensitivity of oxygen evolution under continuous light to variations of pH or the concentration of Ca2+ was altered. Chlorophyll a/b binding proteins serve as light-harvesting antennas. We found in addition that they modulated the activity of water oxidation and, in particular, the protolytic reactions around photosystem II. |
ISSN: | 00062960 | DOI: | 10.1021/bi00147a025 |
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geprüft am 01.06.2024