Laser flash photolysis of 124-kilodalton oat phytochrome in H/sub 2/O and D/sub 2/O solutions: formation and decay of the I/sub 700/ intermediates

Journal Article · Tue Mar 10 04:00:00 EST 1987 · Biochemistry; (United States)

OSTI ID:6220669

Aramendia, P F; Ruzsicska, B P; Braslavsky, S E; Schaffner, K

The transient absorbance difference (..delta..A) after laser flash photolysis of the red-absorbing form (P/sub r/) of 124-kDa oat phytochrome in H/sub 2/O and D/sub 2/O buffers was monitored at 696 nm in the temperature range 265-297 K. When extrapolating back to zero time, the value thus obtained for ..delta..A was unaffected by temperature and the H/sub 2/O/D/sub 2/O change. Furthermore, the flash energy dependence was similar in both buffers. These observations are consistent with the hypothesis that no proton transfer takes place in the primary photoreaction initiating the transformation of P/sub r/ to the far-red-absorbing form of phytochrome, in agreement with the preceding paper on a study of fluorescence lifetimes and quantum yields in the same buffer systems. The first-order decay rate constants of the I/sub 700//sup i/ transients, formed as the primary photoproducts of P/sub r/, are 20% lower in D/sub 2/O. This is compatible with a solvent H/D isotope effect but rather too small for an isotope effect on a proton transfer at room temperature in the transformation of I/sub 700//sup i/ to subsequent products.

• Research Organization: Max-Planck-Institute fuer Strahlenchemie, Muelheim an der Ruhr, West Germany
• OSTI ID: 6220669
• Journal Information: Biochemistry; (United States), Journal Name: Biochemistry; (United States) Vol. 26:5; ISSN BICHA
• Country of Publication: United States
• Language: English

Related Subjects

550201* -- Biochemistry-- Tracer Techniques
59 BASIC BIOLOGICAL SCIENCES
AQUEOUS SOLUTIONS
ARRHENIUS EQUATION
BARYONS
CEREALS
CHEMICAL REACTIONS
DECOMPOSITION
DISPERSIONS
ELEMENTARY PARTICLES
EQUATIONS
FERMIONS
FLUORESCENCE
GRASS
HADRONS
HEAVY WATER
HYDROGEN COMPOUNDS
ISOTOPE EFFECTS
LASERS
LUMINESCENCE
MIXTURES
NEODYMIUM LASERS
NUCLEONS
OATS
ORGANIC COMPOUNDS
OXYGEN COMPOUNDS
PHOTOCHEMICAL REACTIONS
PHOTOLYSIS
PHYTOCHROMES
PIGMENTS
PLANTS
PROTEINS
PROTONS
REACTION INTERMEDIATES
SOLID STATE LASERS
SOLUTIONS
WATER