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| Comparison of Protein Assays; (a2801%, Biuret, Lowry, and Bradford Assays | Colorimetric Assays: Estimated Protein Concentration (mg/mL) for Actual Concentration of 10 mg/mL | |||||
| Protein | Mol.Wt. /103 | pI | 1%
a280nm |
Biuret | Lowry | Bradford |
| Alcohol dehydrogenase (yeast) | 141(4) | 5.4 | 12.6 | 5.8 | 5.0 | 7.8 |
| Alkaline phosphatase
(E. coli) |
89(2) | 4.5 | 7.2 | |||
| a-Amylase | 50+ | - | 26 | 6.8 | 6.0 | 8.3 |
| Asparaginase (E. coli) | 136(4) | 7.1 | ||||
| Bovine serum albumin | 66.2 | 5.2 | 6.6
5.8 |
9.7 | 8.4 | 21.1 |
| Carbonic anhydrase | 29.5 | 5.9 | 18 | 8.8 | 8.9 | 15.2 |
| Catalase | 250(4) | 5.4 | 6.7 | 7.6 | 6.3 | 9.7 |
| a-Chymotrypsin (bovine) | 25 | 9.1
5.2 |
20.4 | 9.4 | 11.6 | 9.5 |
| Cytochrome c (bovine) | 12.3 | 10.6 | 19.2
18.4 |
25.7 | 11.3 | 26.2 |
| Ovalbumin | 45 | 4.6 | 7.5
5.1 |
10.2 | 10.1 | 11.6 |
| Fibrinogen (bovine) | 330 | 13.6 | 6.2 | 7.3 | 7.8 | |
| Gamma globulin (bovine) | 155(2+2) | 6.6 | 13.8 | 10.0* | 10.0* | 10.0* |
| Gamma globulin (rabbit) | 155(2+2) | 6.6 | 13.8 | 9.4 | 11.8 | 8.9 |
| b-Galactosidase | 540(4) | 20.9 | 9.5 | 9.9 | 7.9 | |
| Hemoglobin (bovine) | 66(4) | 6.8 | 16.2 | 8.3 | 19.9 | |
| Histones | 11-21 | 16.3 | 9.7 | 9.2 | 22.2 | |
| Hemocyanin | 6.6 | 5.4 | 9.2 | |||
| Lipase (porcine pancreas) | 45-50 | 4.9
5.0 |
30
13.3 |
|||
| Lysozyme (chicken egg white) | 14.4 | 11 | 26.4 | 10.4 | 12.6 | 7.4 |
| Myoglobin | 17 | 7.0 | 17.8 | 13.7 | 7.9 | 24.9 |
| Ovomucoid | 28 | 7.8 | 8.3 | 5.1 | ||
| Papain | 23 | 9.6 | 25 | |||
| Pepsin | 35 | 1.0 | 14.7 | 9.8 | 12.4 | 3.4 |
| Ribonucease (bovine pancreas) | 13.7 | 9.5 | 7.3 | 11.8 | 15.9 | 9.9 |
| Trypsin inhibitor (soybean) | 21.5 | 4.6 | 9.5
6.0 |
9.1 | 10.3 | 10.1 |
| Transferrin (bovine) | 77 | 11.2 | 8.5 | 9.0 | 12.6 | |
| Trypsin (bovine pancreas) | 23.8 | 10.5 | 14.3 | 11.4 | 15.5 | 5.5 |
| Thyroglobulin | 669 | 7.7 | 8.2 | 9.3 | ||
|
|
41.2 | 10.1 | 9.5 | 11.8 | ||
| S.D. | 35 | 4.2 | 2.9 | 6.3 | ||
*All colorimetric assays were performed on appropriate dilutions of
gravimetricalIy prepared 10 mg/mL solutions of commercially obtained proteins.
Bovine gamma globulin was used to define the standard response for the
colorimetric assays. Sources: "Bio-Rad Protein Assay" Technical
Bulletin, Bio-Rad Laboratories; Read & Northcote, (1981) Anal. Biochem.
116:53-64;
Compton & Jones, (1985) Anal. Biochem. 151:369-374; Peterson,
(1983) Methods Enzymol. 91:95-119.