PHOTOACTIVITY OF TRANSIENT INTERMEDIATES IN THE PATHWAY FROM THE RED‐ABSORBING TO THE FAR‐RED‐ABSORBING FORM OF Avena PHYTOCHROME AS OBSERVED BY A DOUBLE‐FLASH TRANSIENT‐SPECTRUM ANALYZER

Abstract— Phototransformation from the red‐absorbing form of phytochrome (Pr) to the far‐red‐absorbing form occurs via at least two reaction stages. We report here on the photoactivity of the intermediates present during these two stages, as detected with 114/118‐kdalton Avena phytochrome by a transient spectrum analyzer with two actinic lasers of microsecond duration. Flash activation of intermediates present during the first stage results in their photoconversion back to Pr within the time resolution provided by the analyzer, which is 10 μs. Since these intermediates are present within 60 ns of excitation of Pr (Cordonnier et al., 1981), a single flash of ms duration as used here should yield a photostationary equilibrium between them and Pr. The proportion of Pr converted to intermediates by a single saturating flash is estimated to be about 30%. Flash activation of intermediates present during the second stage converts them to another transient intermediate stage, which decays thermally to Pr within 2 ms.

[1]  M. Furuya,et al.  ANALYSIS OF PHOTOTRANSFORMATION INTERMEDIATES IN THE PATHWAY FROM THE RED‐ABSORBING TO THE FAR‐RED‐ABSORBING FORM OF AVENA PHYTOCHROME BY A MULTICHANNEL TRANSIENT SPECTRUM ANALYZER , 1982 .

[2]  L. Kerscher,et al.  Western blot analysis of a lytic process in vitro specific for the red light absorbing form of phytochrome , 1982 .

[3]  P. Quail,et al.  Native phytochrome: Inhibition of proteolysis yields a homogeneous monomer of 124 kilodaltons from Avena. , 1982, Proceedings of the National Academy of Sciences of the United States of America.

[4]  M. Furuya,et al.  Phototransformation of the Far-red Light-absorbing Form of Large Pea Phytochrome by Laser Flash Excitation , 1982 .

[5]  L. Pratt,et al.  Immunopurification and initial characterization of dicotyledonous phytochrome. , 1982, Plant physiology.

[6]  L. Pratt,et al.  PHOTOTRANSFORMATION KINETICS OF UNDEGRADED OAT AND PEA PHYTOCHROME INITIATED BY LASER FLASH EXCITATION OF THE RED‐ABSORBING FORM , 1981 .

[7]  M. Furuya,et al.  Phototransformation of the red-light-absorbing form of undegraded pea phytochrome by laser flash excitation. , 1980, Plant & cell physiology.

[8]  K. Schaffner,et al.  CHARACTERIZATION OF A MICROSECOND INTERMEDIATE IN THE LASER FLASH PHOTOLYSIS OF SMALL PHYTOCHROME FROM OAT , 1980 .

[9]  L. Pratt,et al.  Phytochrome immunoaffinity purification. , 1979, Plant physiology.

[10]  R. E. Kendrick,et al.  PHOTOTRANSFORMATIONS OF PHYTOCHROME , 1977, Photochemistry and photobiology.

[11]  L. Pratt.  PHOTOCHEMISTRY OF HIGH MOLECULAR WEIGHT PHYTOCHROME IN VITRO * , 1975, Photochemistry and photobiology.

[12]  L. Pratt.  Comparative immunochemistry of phytochrome. , 1973, Plant physiology.

[13]  J. Karemaker,et al.  Tension Transients after Quick Release in Rat and Frog Skeletal Muscles , 1972, Nature.

[14]  W. L. Butler,et al.  THE TEMPERATURE DEPENDENCE OF PHYTOCHROME TRANSFORMATIONS , 1970, Photochemistry and photobiology.

[15]  W. L. Butler,et al.  STABILIZATION OF PHYTOCHROME INTERMEDIATES BY LOW TEMPERATURE * , 1968, Photochemistry and photobiology.

[16]  V. Kasche,et al.  Low-temperature studies on phytochrome: light and dark reactions in the red to far-red transformation and new intermediate forms of phytochrome. , 1968, Proceedings of the National Academy of Sciences of the United States of America.

[17]  V. Kasche,et al.  KINETICS OF PHYTOCHROME CONVERSION: MULTIPLE PATHWAYS IN THE P(r) TO P(fr) REACTION, AS STUDIED BY DOUBLE-FLASH TECHNIQUE. , 1967, Proceedings of the National Academy of Sciences of the United States of America.

[18]  V. Kasche,et al.  The kinetics of phytochrome conversion. , 1966, The Journal of biological chemistry.

[19]  S. Hendricks,et al.  ACTTON SPECTRA OF PHYTOCHROME IN VITRO * , 1964 .

[20]  A. Savitzky,et al.  Smoothing and Differentiation of Data by Simplified Least Squares Procedures. , 1964 .