THE FORMATION OF A SHORT-WAVELENGTH CHLOROPHYLLIDE FORM AT PARTIAL PHOTOTRANSFORMATION OF PROTOCHLOROPHYLLIDE IN ETIOPLAST INNER MEMBRANES

Abstract

Abstract— Partial phototransformation caused the formation and successive accumulation of spectral forms of chlorophyllide in etioplast inner membrane fractions from wheat (Triticum aestivum L. cv. Walde), Low-temperature fluorescence emission and circular dichroism spectra showed the formation of two chlorophyllide forms with emission maxima at 683 and 694 nm, respectively. The light dependent accumulation of the two forms differed in prolamellar body (PLB) and prothylakoid (PT) fractions. The 694 nm form was preferentially found in PLB fractions which before irradiation were characterized by a 657 nm emitting protochlorophyllide form and a regular PLB structure. The 683 nm form accumulated to a higher extent in PT fractions which before irradiation contained mainly shortwavelength protochlorophyllide forms. The results indicate that at least two photoactive protochlorophyllide forms must be considered. The major part of protochlorophyllide, with a fluoresence emission maximum at 657 nm, is transformed to the 694 nm emitting chlorophyllide first at high light doses. A minor part, revealed only after Gaussian resolution, has a fluorescence emission maximum at 645 nm and was transformed by low light doses to chlorophyllide emitting at 683 nm.