title: Photosystem II reaction center with altered pigment-composition: reconstitution of a complex containing five chlorophyll a per two pheophytin a with modified chlorophylls.
abstract: Pigment-depleted Photosystem II reaction centers (PS II-RCs) from a higher plant (pea) containing five chlorophyll a (Chl) per two pheophytin a (Phe), were treated with Chl and several derivatives under exchange conditions [FEBS Lett. 434 (1998) 88]. The resulting reconstituted complexes were compared to those obtained by pigment exchange of "conventional" PS II-RCs containing six Chl per two Phe. (1) The extraction of one Chl is fully reversible. (2) The site of extraction is the same as the one into which previously extraneous pigments have been exchanged, most likely the peripheral D1-H118. (3) Introducing an efficient quencher (Ni-Chl) into this site results in only 25% reduction of fluorescence, indicating incomplete energy equilibration among the "core" and peripheral chlorophylls.
mesh_terms: D001665:Binding Sites; D002734:Chlorophyll / Q000737:chemistry*; D002851:Chromatography, High Pressure Liquid; D002942:Circular Dichroism; D004735:Energy Transfer; D045342:Light-Harvesting Protein Complexes; D018532:Pisum sativum; D010674:Pheophytins / Q000737:chemistry*; D045322:Photosynthetic Reaction Center Complex Proteins / Q000737:chemistry*; D045332:Photosystem II Protein Complex; D010860:Pigments, Biological / Q000032:analysis / Q000737:chemistry*; D018515:Plant Leaves; D013050:Spectrometry, Fluorescence; D013056:Spectrophotometry, Ultraviolet
chemical_list: D045342:Light-Harvesting Protein Complexes; D010674:Pheophytins; D045322:Photosynthetic Reaction Center Complex Proteins; D045332:Photosystem II Protein Complex; D010860:Pigments, Biological; D002734:Chlorophyll; C061694:pheophytin a