Accuracy of molecular mass determination of proteins in solution by small-angle X-ray scattering

Mylonas E, Svergun D, Journal of Applied Crystallography 40(s1):s245-s249 (2007) DOI

SASDA98 – Thyroglobulin in Tris/HCl

MWI(0) 622 kDa
MWexpected 606 kDa
log I(s) 2.51×103 2.51×102 2.51×101 2.51×100
Thyroglobulin small angle scattering data  s, nm-1
ln I(s)
Thyroglobulin Guinier plot ln 2.51×103 Rg: 7.9 nm 0 (7.9 nm)-2 s2
Thyroglobulin Kratky plot 1.104 0 3 sRg
Thyroglobulin pair distance distribution function Rg: 7.4 nm 0 Dmax: 24 nm

Data validation

Fits and models

log I(s)
 s, nm-1
Thyroglobulin DAMMIN model

Synchrotron SAXS data from solutions of Thyroglobulin in Tris/HCl in 100 mM Tris/HCl 100 mM NaCl, pH 7.5 were collected on the EMBL X33 beam line at the DORIS III storage ring (Hamburg, Germany) using a MAR 345 Image Plate detector (I(s) vs s, where s = 4πsinθ/λ, and 2θ is the scattering angle). One solute concentration of 3.90 mg/ml was measured at 20°C. The data were normalized to the intensity of the transmitted beam and radially averaged; the scattering of the solvent-blank was subtracted.

Thyroglobulin contains glycans and extra iodines, for these reasons the molecular weight based on the sequence (606 kDa) does not agree with the experimentally calculated one (622 kDa).

Mol. type   Protein
Organism   Bos taurus
Olig. state   Dimer
Mon. MW   303.2 kDa
UniProt   P01267
Sequence   FASTA