Table 1.
Biochemical and Biological Activity of purified IFNα subtypes.
| IFNα Subtype | Molecular Weight Determination
|
Biological Activity
|
||||
|---|---|---|---|---|---|---|
| Theoretical | Mass spectrometry | Δ (Da.) | Gel filtration | EC50 (pM) | Specific activity (IU/mg) | |
| IFNα1a | 19,574 | 19,536 | 38 | 20,423 | 222.4 ± 19.5 | 3.0 ± 0.2×107† |
| IFNα2a | 19,429 | 19,431 | 2 | 21,649 | 8.4 ± 1 | 4.3 ± 0.4×108† |
| IFNα2b | 19,457 | 19,437 | 20 | 24,469 | 7.8 ± 1.4 | 5.1×108 |
| IFNα4 | 19,567 | 19,534 | 33 | 18,389 | 40 ± 4.3 | 9.9 ± 0.6×107† |
| IFNα5 | 19,712 | 19,756 | 44 | 18,713 | 8.2 ± 1.2 | 4.8×108 |
| IFNα6 | 19,934 | 19,899 | 34 | 25,637 | 7.8 ± 0.74 | 5.1×108 |
| IFNα7 | 19,795 | 19,772 | 23 | 17,348 | 29.7 ± 4.7 | 1.3×108 |
| IFNα8 | 19,672 | 19,642 | 30 | 23,628 | 3.1 ± 0.6 | 1.3×109 |
| IFNα10 | 19,594 | 19,562 | 32 | 15,711 | 1.8 ± 0.3 | 2.2×109 |
| S-IFNα14 | 19,896 | 19,854 | 42 | 18,710 | 1.4 ± 0.2 | 3.1 ± 0.3×109† |
| R-IFNα14 | 19,896 | N.D. | N.D. | 18,701 | 1 ± 0.1 | 4.0×109 |
| IFNα16 | 19,470 | 19,466 | 4 | 21,523 | 8.5 ± 1 | 4.7×108 |
| IFNα17 | 19,487 | 19,482 | 5 | 15,803 | 4.7 ± 1 | 8.4×108 |
| IFNα21 | 19,500 | 19,496 | 4 | 15,260 | 10.9 ± 1.1 | 3.6×108 |
| IFNα1a* | N.D. | N.D. | N.D. | N.D. | 110 ± 7 | 3.6×107 |
| IFNα8* | N.D. | N.D. | N.D. | N.D. | 3.7 ± 0.5 | 1.1×109 |
| IFNα14* | ND | ND. | N.D. | N.D. | 5.4 ± 0.6 | 7.3×108 |
S-IFNα14, obtained from soluble SPD-IFNα14; R-IFNα14, obtained from refolded SPD-IFNα14;
†
mean specific activity derived from 3 different expression/purification experiments;
*
IFNα’s purchased from commercial source; N.D., Not Determined; Specific activity was calculated using IFNα2a NIH standard.