Anti-Stokes fluorescence excitation reveals conformational mobility of the C-phycocyanin chromophores

Tsoraev G, Protasova E, Klimanova E, Ryzhykau Y, Kuklin A, Semenov Y, Ge B, Li W, Qin S, Friedrich T, Sluchanko N, Maksimov E, Structural Dynamics 9(5):054701 (2022) DOI

SASDPA4 – SAXS data for the trimeric C-phycocyanin

C-phycocyanin alpha subunit
C-phycocyanin beta subunit
MWexperimental 124 kDa
MWexpected 107 kDa
VPorod 154 nm3
log I(s) 9.60×10-1 9.60×10-2 9.60×10-3 9.60×10-4
C-phycocyanin alpha subunit C-phycocyanin beta subunit small angle scattering data  s, nm-1
ln I(s)
C-phycocyanin alpha subunit C-phycocyanin beta subunit Guinier plot ln 9.60×10-1 Rg: 3.9 nm 0 (3.9 nm)-2 s2
(sRg)2I(s)/I(0)
C-phycocyanin alpha subunit C-phycocyanin beta subunit Kratky plot 1.104 0 √3 sRg
p(r)
C-phycocyanin alpha subunit C-phycocyanin beta subunit pair distance distribution function Rg: 3.9 nm 0 Dmax: 13.2 nm

Data validation

Fits and models

log I(s)
 s, nm-1
C-phycocyanin alpha subunit C-phycocyanin beta subunit GASBOR model
SAXS data from solutions of SAXS data for the trimeric C-phycocyanin in 150 mM NaCl, 20 mM Tris, pH 7.6 were measured using a Rigaku MicroMax 007-HF instrument at the Moscow Institute of Physics and Technology (MIPT; Russian Federation) equipped with a multiwire gas-filled ASM DTR Triton 200 detector at a sample-detector distance of 2 m and at a wavelength of λ = 0.154 nm (I(s) vs s, where s = 4πsinθ/λ, and 2θ is the scattering angle). One solute concentration of 15.20 mg/ml was measured at 20°C. One 10800 second frame was collected. The data were normalized to the intensity of the transmitted beam and radially averaged; the scattering of the solvent-blank was subtracted.

Spirulina platensis C-phycocyanin is composed of alpha and beta subunits. This complex forms ring-shaped trimers at 150 mM NaCl.

C-phycocyanin alpha subunit (cpcA)
Mol. type   Protein
Organism   Arthrospira platensis
Olig. state   Trimer
Mon. MW   17.6 kDa
 
UniProt   P72509 (1-162)
Sequence   FASTA
 
C-phycocyanin beta subunit (cpcB)
Mol. type   Protein
Organism   Arthrospira platensis
Olig. state   Trimer
Mon. MW   18.1 kDa
 
UniProt   P72508 (1-172)
Sequence   FASTA