Table 1.
Proteins surveyed in this work and concentrations of SDS at which they denature
| Protein | Enzyme accession no. | Molecular weight | No. of subunits | pl | [SDS]Δμ |
|---|---|---|---|---|---|
| Albumin, human | P02768 | 66.5 | 1 | 5.7 | 0.1 |
| Hemoglobin A | P69905 and P68871 | 64.5 | 4 (two α- and two β-chains) | 7.2 | 0.2 |
| Alcohol dehydrogenase | P00330 | 146.8 | 4 | 5.6 | 0.2 |
| Pyruvate kinase | P11974 | 231.6 | 4 | 7.6 | 0.2 |
| Ubiquitin | P62990 | 8.6 | 1 | 6.6 | 0.4 |
| Myoglobin | P68082 | 17.0 | 1 | 7.4 | 0.4 |
| α-Lactalbumin | P00711 | 14.2 | 1 | 4.8 | 0.6 |
| β-LgbA* | P02754 | 18.4 | 1 | 4.8 | 1.0 |
| β-LgbB* | P02754 | 18.3 | 1 | 4.8 | 1.6 |
| Ovalbumin | P01012 | 42.8 | 1 | 5.2 | 2.0 |
| Creatine phosphokinase | P00563 | 86.2 | 2 | 6.7 | 3.0 |
| BCA | P00921 | 30.0 | 1 | 5.9 | 5.0 |
| Carboxypeptidase B | P09955 | 34.7 | 1 | 5.7 | 5.0 |
| 4 (two heavy and two light chains, all S-S-linked) | |||||
| IgG | Mixture of all | ≈150.0 | 5.0 | ||
| Bovine antibodies | |||||
| Cytochrome c | 12.4 | 1 | 9.6 | ? | |
| Lysozyme | P00698 | 14.0 | 1 | 10.7 | ? |
| SOD | P00442 | 31.1 | 2 | 5.9 | >10 |
| Streptavidin | P22629 | 65.6 | 4 | 6.9 | >10 |
The molecular weights listed are for the entire protein (not per subunit). All of the data for the molecular weight, number of subunits, and pl come from the Swiss-Prot database. The number of subunits is the number of polypeptide chains comprising the protein, or, equivalently, the number of polypeptide chains that appear in a denaturing and reducing SDS/PAGE experiment. [SDS]Δμ refers to the concentration of SDS at which the peak in the electropherogram corresponding to the native protein disappears in our experiments (60-cm capillary, 30 kV). This value depends on the time the protein spends in the capillary and may change with a capillary of a different length or applied voltage. The critical micelle concentration of SDS in the Tris-Gly buffer used in these experiments (pH 8.3) is 4.3 mM (17). The question marks refer to proteins that, because of their positive charge, cannot be observed until they bind enough molecules of SDS to be negatively charged. We cannot, therefore, determine a concentration of SDS at which the mobility of these proteins begins to change.