Abstract
A rapid and sensitive method for estimating proteins using an alkaline copper sulfate reagent is described. The method is reasonably nonspecific for type of protein and can be used for solutions containing DNA even at concentrations of the latter as high as 0.7 mg/ml in the final reaction mixture. In the presence of DNA, 0.15 to 3.0 mg of protein can be estimated and in the absence of DNA, as little as 0.075 mg. The effects are described of various salts, of perchloric acid, and of urea on the estimation. Measurements on several dipeptides showed that proline peptides do not form ultraviolet-absorbing complexes with copper whereas prolyl peptides do form such complexes. This explains the finding that gelatin (which has a high proportion of proline and of hydroxyproline residues) is less reactive with copper than are the other proteins studied here. © 1964.
| Original language | English |
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| Pages (from-to) | 401-410 |
| Number of pages | 9 |
| Journal | Analytical Biochemistry |
| Volume | 9 |
| Issue number | 4 |
| Publication status | Published - Dec 1964 |