Phototransformation of protochlorophyllideF657 in etiochloroplasts isolated from pine cotyledons; dark reformation of this pigment-complex from a pool of ALA-protochlorophyllideF635 in the presence of NADPH.

Etiochloroplasts isolated from dark-grown pine cotyledons fed with δ-aminolevulinic acid (ALA Abbreviations: ALA=\Gd-aminolevulinic acid; Chl(ide) = chlorophyll(ide); PChlide = protochlorophyllide; PChlideA636, PChlideA650=forms of protochlorophyllide absorbing light maximally at the wavelength indicated in nm; PChlideF635, PChlideF657=PChlide forms exhibiting a fluorescence maximum at the wavelength indicated; ALA-Pchlide=PChlide formed by an exogenous ALA treatment; NADPH = nicotineamide adeninedinucleotide phosphate. ) contain, in addition to the chlorophyll forms, two protochlorophyllide complexes which emit fluorescence around 635 nm and 657 nm respectively (ALA-PChlideF635 and PChlideF657). By a combination of light flashes and periods of darkness, it is possible to phototransform PChlideF657 and thereafter, if NADPH is added to the system, to re-form this pigment-complex from the pool of ALA-PChlideF635 during the dark periods. The process of phototransformation followed by the re-formation of PChlideF657 in the presence of NADPH can be obtained in vitro five to six times consecutively. The role of NADPH in the formation of the PChlideF657 complex is discussed.