title: Photoactive pigment-enzyme complexes of chlorophyll precursor in plant leaves.
abstract: This review summarizes contemporary data on structure and function of photoactive pigment--enzyme complexes of the chlorophyll precursor that undergoes photochemical transformation to chlorophyllide. The properties and functions of the complex and its principal components are considered including the pigment (protochlorophyllide), the hydrogen donor (NADPH), and the photoenzyme protochlorophyllide oxidoreductase (POR) that catalyzes the photochemical production of chlorophyllide. Chemical variants of the chlorophyll precursor are described (protochlorophyllide, protochlorophyll, and their mono- and divinyl forms). The nature and photochemical activity of spectrally distinct native protochlorophyllide forms are discussed. Data are presented on structural organization of the photoenzyme POR, its substrate specificity, localization in etioplasts, and heterogeneity. The significance of different POR forms (PORA, PORB, and PORC) in adaptation of chlorophyll biosynthesis to various illumination conditions is considered. Attention is paid to structural and functional interactions of three main constituents of the photoactive complex and to possible existence of additional components associated with the pigment-enzyme complex. Historical aspects of the problem and the prospects of further investigations are outlined.
authors.affiliation: Faculty of Biology, Lomonosov Moscow State University, 119991 Moscow, Russia. olgabelyaeva@mail.ru
authors.forename: O B
authors.initials: OB
authors.lastname: Belyaeva
authors.forename: F F
authors.initials: FF
authors.lastname: Litvin
mesh_terms: D002734:Chlorophyll / Q000031:analogs & derivatives* / Q000737:chemistry; D004926:Escherichia coli / Q000378:metabolism; D005415:Flavins / Q000737:chemistry; D008956:Models, Chemical; D008968:Molecular Conformation; D044925:Oxidoreductases Acting on CH-CH Group Donors / Q000737:chemistry; D010858:Pigmentation; D018515:Plant Leaves / Q000378:metabolism*; D010940:Plant Proteins / Q000737:chemistry* / Q000378:metabolism; D010944:Plants / Q000378:metabolism; D011487:Protein Conformation; D017433:Protein Structure, Secondary; D011521:Protochlorophyllide / Q000737:chemistry*; D013379:Substrate Specificity; D013696:Temperature
chemical_list: D005415:Flavins; D010940:Plant Proteins; D002734:Chlorophyll; C016083:protochlorophyll; D011521:Protochlorophyllide; D044925:Oxidoreductases Acting on CH-CH Group Donors; C023886:protochlorophyllide reductase