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STUDIES ON THE PROTEIN CONFORMATION OF PHYTOCHROME
Author(s) -
Tobin Elaine M.,
Briggs Winslow R.
Publication year - 1973
Publication title -
photochemistry and photobiology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.818
H-Index - 131
eISSN - 1751-1097
pISSN - 0031-8655
DOI - 10.1111/j.1751-1097.1973.tb06454.x
Subject(s) - phytochrome , chromophore , circular dichroism , random coil , absorbance , optical rotatory dispersion , tryptophan , fluorescence , chemistry , phytochrome a , photochemistry , biophysics , crystallography , amino acid , biology , biochemistry , botany , optics , physics , chromatography , red light , arabidopsis , gene , mutant
— The extinction coefficients for large rye phytochrome were found to be: Fluorescence and circular dichroism spectra of large‐ and small‐molecular‐weight rye phytochrome give no evidence for a protein conformational change on phototransformation of phytochrome. The large molecule has a fluorescence emission peak at 331 nm when excited at 290 nm, and an excitation peak for this emission at 288 nm. The circular dichroism spectra indicate that large rye phytochrome has about 17–20% a‐helix content, 30%β‐structure and 50% random coil, and that the small rye phytochrome has about 10–13%α‐helix content. The ultraviolet difference spectra for large and small rye phytochrome are similar and differ from the difference spectrum of the small oat phytochrome in the relative size of the 296–298 nm peak. The difference spectra may reflect changes in chromophore absorbance and in the environment of amino acid residues near the chromophore, particularly of tyrosine, and perhaps of tryptophan and cysteine.