Spectral properties and chromophore rotation of phytochrome bound to substituted Sepharose |
| |
Authors: | Christer Sundqvist Nils G. A. Ekelund |
| |
Affiliation: | Dept of Plant Physiology, Botanical Institute, Carl Skottsbergs Gata 22, S-413 19 Göteborg, Sweden;Dept of Plant Physiology, Univ. of Lund, P.O. Box 7007, S-220 07 Lund, Sweden. |
| |
Abstract: | Brushite purified phytochrome from Avena sativa L. cv. Sol II was bound to phenyl Sepharose, octyl Sepharose, CNBr-activated Sepharose and to anti-phytochrome immunoglobulins immobilized on Sepharose. The spectral properties of phytochrome bound to anti-phytochrome immunoglobulins and to phenyl Sepharose were similar to phytochrome in solution. Phytochrome bound to CNBr-activated Sepharose or to octyl Sepharose showed reduced Pfr formation after red irradiation. The reversal to Pr with far-red light was only partial but a further increase at 667 nm took place slowly in the dark. A peak at 657 nm was seen in the difference spectrum between CNBr-activated Sepharose-bound phytochrome kept in darkness and the identical sample immediately after a far-red irradiation. The change in linear dichroism at 660 nm and 730 nm, induced by plane polarized red or far-red light, was measured. It was computed that the long-wavelength transition moment of phytochrome had an average rotation angle of 31.5° or 180°–31.5°. The substrate used for immobilization had a limited effect on the rotation angle. Phytochrome immobilized on CNBr-activated Sepharose gave an angle of 27.8° and phytochrome immobilized on phenyl Sepharose gave an angle of 32.6°. |
| |
Keywords: | Avena sativa linear dichroism phytochrome intermediates |
|
|