Low temperature phototransformations of protochlorophyll(ide) in etiolated leaves

✍ Scribed by N. V. Ignatov; O. B. Belayeva; F. F. Litvin

• Book ID: 104641076
• Publisher: Springer
• Year: 1993
• Tongue: English
• Weight: 667 KB
• Volume: 38
• Category: Article
• ISSN: 0166-8595
• DOI: 10.1007/bf00146410

✦ Synopsis

By methods of difference and derivative spectroscopy it was shown that in etiolated leaves at 77 K three photoreactions of P650 protochlorophyllide take place which differ in their rates and positions of spectral maxima of the intermediates formed in the process: P650→R668, P650→R688, and P650→R697. With an increase of temperature up to 233 K, in the dark, R688 and R697 are transformed into the known chlorophyllide forms C695/684 and C684/676, while R668 disappears with formation of a shorter wavelength form of protochlorophyllide with an absorption maximum at 643-644 nm.Along with these reactions, at 77 K phototransformations of the long-wave protochlorophyllide forms with absorption maxima at 658-711 nm into the main short-wave forms of protochlorophyllide are observed. At 233 K in the dark this reaction is partially reversible. This process may be interpreted as a reversible photodisaggregation of the pigment in vivo.The mechanism of P650 reactions and their role in the process of chlorophyll photobiosynthesis are discussed.