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. 1970 May;45(5):567–570. doi: 10.1104/pp.45.5.567

Immunochemical and Spectroscopic Evidence for Protein Conformational Changes in Phytochrome Transformations

D W Hopkins a, W L Butler a
PMCID: PMC396461  PMID: 16657343

Abstract

Phytochrome was examined by immunochemical and spectroscopic techniques to detect differences between the protein moieties of red- and far red-absorbing phytochrome (Pr and Pfr). No differences in the reaction of Pr and Pfr with phytochrome antibody were discernible on Ouchterlony double diffusion plates. However, the microcomplement fixation assay showed a greater degree of antibody reaction with Pfr than with Pr, indicating some difference in the surface characteristics of the two forms. Circular dichroism spectroscopy between 300 and 200 nanometers revealed differences between Pr and Pfr which may reflect differences in the protein conformation. The circular dichroism spectrum of Pr showed a negative band at 285 nanometers which was not present in the spectrum of Pfr, and the large negative circular dichroism band at 222 nanometers with Pfr, associated with the α-helical content, was shifted 2 nanometers to shorter wave length with Pr although there was no change of magnitude of this band. The absorbancy of Pr and Pfr is very nearly the same in the 280 nanometer spectral region, but sensitive difference spectra between Pr and Pfr did reveal spectra which were similar to solvent perturbation spectra obtained by others with different proteins. In total, the experiments indicate that there are conformational differences between the protein moieties of Pr and Pfr but that these differences are rather slight from a standpoint of gross structure.

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Selected References

These references are in PubMed. This may not be the complete list of references from this article.

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