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Photokinetic and photophysical parameters of the blue light induced phototransformation of phytochrome in the presence of flavin
Author(s) -
Appenroth KlausJ.,
Hermann Gudrun,
Augsten Helmut,
Müller Eberhard
Publication year - 1985
Publication title -
physiologia plantarum
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.351
H-Index - 146
eISSN - 1399-3054
pISSN - 0031-9317
DOI - 10.1111/j.1399-3054.1985.tb04262.x
Subject(s) - phytochrome , flavin group , flavin mononucleotide , reaction rate constant , chemistry , photochemistry , kinetics , enzyme , biochemistry , biology , red light , physics , botany , quantum mechanics
Flavin mononucleotide (FMN) transfers its excitation energy to phytochrome Pr with a rate constant <8.7 × 1011 I mol‐1 s‐1. This reaction is not specific for Pr. the transfer to the phytochrome Pfr proceeds with ?5.8 × 1011 1 mol‐1 s‐1. These rate constants are lower limits because the complex‐formation constants are unknown. Assuming a horsier energy transfer a greater complex‐formation constant, as well as a greater orientation factor or a smaller distance in the complex FMN‐Pfr than in FMN‐Pr would be the possible reason for the difference between the rate constants. It is shown that the “flavin effect” can only be of physiological relevance if the local phytochrome concentration does not reach the millimolar range at the same place Under these conditions the reaction Pr Pfr proceeds more effectively, but the reaction Pr Pfr less effectively than in the absence of the donor FMN. which gives rise to a shift of the equilibrium in favour of Pfr.