Dependence of catalase photoinactivation in rye leaves on light intensity and quality and characterization of a chloroplast-mediated inactivation in red light

摘要: In green or etiolated rye leaves catalase was most efficiently inactivated by blue light absorbed its prosthetic heme. Red ineffective at low intensity but induced marked inactivation in higher photon flux, while far-red ineffective. At identical intensities of photosynthetically active radiation, Photosystem II (PS II) equally both and red light. Since insensitive to no sensitizer for detected isolated peroxisomes, the observed must result from photooxidative reactions initiated chloroplasts. a simplified model system presence suspension either intact broken chloroplasts This chloroplast-mediated vitro O2-dependent. It greatly retarded temperature, fully suppressed radic al scavenger Trolox, partially superoxide dismutase, only little diminished singlet oxygen quencher histidine not affected dimethylsulfoxide, hydroxyl radical scavenger. Chloroplast-mediated suitable electron acceptors, particular methyl viologen. A comparison effects inhibitors, donors, acceptors specific sites photosynthetic transport indicated that an overreduction PS plastoquinone represented major sources formation O2ċ some unidentified appeared mediate outside provides means detection redox signalling postulated indicate plastoquinones. Similarly as system, also temperature-dependent stimulated DBMIB (2,5-dibromo-3-methyl-6-isopropyl-p-benzoquinone). These results provide strong evidence chloroplastic occurred under conditions vitro.