Table 1.
Sedimentation properties of apoferritin and ferritin
| Sample | AUC method | s20,w (S) | Molar mass M (kDa) | (mL/g) | B1 (g/g) |
|---|---|---|---|---|---|
| Apoferritin | SV | 17.16 | 500 ± 20 | 0.7338a | -- |
| SE | -- | 480 ± 9b | 0.732 ± 0.016c | 0.23 ± 0.1c | |
| Ferritin | |||||
| Sigma-5 | SV | 26.9 | -- | ||
| Sigma-8 | SV | 39.2 | 700 | 0.564d | -- |
| Sigma-11 | SV | 51.6 | 760 | 0.484d | -- |
| Sigma-14 | SV | 59.0 | 840 | 0.457d | -- |
| Sigma-17 | SV | 60.0 | 890 | 0.463d | -- |
| Amersham-14 | SV | 70.4 | 970 | 0.426d | -- |
| SE | -- | 900 ± 40e | -- | -- | |
| Amersham-15 | SV | 71.7 | 980 | 0.422d | -- |
| SE | -- | 920 ± 45e | -- | -- | |
| Amersham-16 | SV | 72.1 | 980 | 0.419d | -- |
| SE | -- | 960 ± 60e | 0.41 ± 0.23c | 0.50 ± 0.24c | |
| Amersham-17 | SV | 69.8 | 950 | 0.420d | -- |
| SE | -- | 890 ± 40e | -- | -- |
Partial specific volume calculated based on the amino acid sequence. The correction to s20,w is based on the partial specific volume indicated within the same row.
Molar mass determined by sedimentation equilibrium is based on the amino acid sequence partial specific volume. The error is based on three determinations at different loading concentrations.
Parameters determined by sucrose density contrast sedimentation equilibrium. Errors are based on errors in the slope and intercept of the best-fit straight line to a plot of buoyant molar mass versus density. For the purposes of the calculation, the ferritin sample was assumed to have a full complement of iron.
Molar mass and partial specific volume based on sedimentation velocity data fit to a c(s) distribution of sedimenting species in which the frictional coefficient is fixed at 1.27. The correction to s20,w is based on the best-fit partial specific volume indicated within the same row. Note that in the case of Sigma-5, the presence of apoferritin complicated the determination of the molar mass and partial specific volume for the 26.9 S species, representing a partially filled ferritin.
Molar mass based on a partial specific volume of 0.422 mL/g, representing the average best-fit value for Amersham fractions 14 – 17 determined by sedimentation velocity. The error is based on data from two loading concentrations.