title: In photoinhibited photosystem II particles pheophytin photoreduction remains unimpaired.
abstract: Oxygen-evolving photosystem II particles (DT 20) isolated from pea chloroplasts by digitonin-Triton X-100 fractionation were photoinhibited with 150 W. m(-2) white light, at 20°C under three conditions: aerobic, anaerobic and strongly reducing (E(h) poised to approx. -250 mV with dithionite). Hill reaction rate (H (20) + BQ)and variable fluorescence (Fv) declined in parallel in all three cases with shortening half times: 30, 10 and 2.5 min, respectively. Light-induced absorbance changes at 685 nm characteristic of reversible photo accumulation of reduced pheophytin (& z -2.50 mV) remained essentially unchanged. We conclude that the three types of photoinhibitory treatment do not impair the separation of charges between chlorophyll P-680 and pheophytin in the photosystem II reaction center.
authors.affiliation: Institute of Soil Science and Photosynthesis, USSR Academy of Sciences, 142292 Pushchino, USSR.
authors.forename: S I
authors.initials: SI
authors.lastname: Allakhverdiev
authors.forename: E
authors.initials: E
authors.lastname: Šetliková
authors.forename: V V
authors.initials: VV
authors.lastname: Klimov
authors.forename: I
authors.initials: I
authors.lastname: Šetlik
mesh_terms: D000332:Aerobiosis; D000693:Anaerobiosis; D005453:Fluorescence; D008027:Light; D010084:Oxidation-Reduction; D018532:Pisum sativum / Q000378:metabolism / Q000502:physiology* / Q000528:radiation effects; D010674:Pheophytins / Q000378:metabolism*; D045332:Photosystem II Protein Complex / Q000378:metabolism*; D013997:Time Factors
chemical_list: D010674:Pheophytins; D045332:Photosystem II Protein Complex