Data for: Circular dichroism spectroscopy reveals multiple phytochrome photoproducts in equilibrium

This work involves characterization of the model cyanobacterial phytochrome photoreceptor Cph1 from Synechocystis sp. PCC6803, using characterization of different truncations and variant proteins constructed using site-directed mutagenesis. Wild-type Cph1 photoconverts between two photostates: a red-absorbing, dark-adapted Pr state in which the phycocyanobilin (PCB) chromophore is in the 15Z configuration, and a far-red-absorbing Pfr photoproduct in which PCB is instead in the 15E configuration. Proteins were characterized using absorption and circular dichroism spectroscopy. Absorption spectra were taken under native and denaturing conditions. Absorption and circular dichroism (CD) spectra were also taken at different pH values. All variants were examined after recombinant co-expression with enzymes for the synthesis of PCB in E. coli. One additional variant was also examined after expression and purification without chromophore biosynthesis, followed by in vitro assembly with PCB., Absorption spectra were acquired using Cary 50 or Cary 60 spectrophotometers.
CD spectra were acquired using an Applied Photophysics Chirascan circular dichroism spectrometer., # Data for: Circular dichroism spectroscopy reveals multiple phytochrome photoproducts in equilibrium

## Description of the Data and file structure

Data are deposited as a gzipped tarball containing a series of tab-delimited text files with Unix newlines. After extraction, the deposited data are in six folders:
I. Standard_native_absorption
II. Standard_CD
III. In_vitro_assembly
IV. Estimated_photoisomerization
V. Analysis_of_CD
VI. Analysis_of_pH_effects

### I. Standard\_native\_absorption:

This folder contains absorption spectra for purified proteins after co-expression with PCB biosynthesis enzymes, measured under standard conditions (pH 7.8). Two wild-type sequences were examined: a truncation having the first 322 N-terminal amino acids (N322), and another having the first 514 amino acids (N514). The N514 construct was also used to construct a series of variant proteins via site-directed mutagenesis. Absorption spectra for each of these proteins are included in this folder, for ...,