Determination of Protein Concentration
Given the importance of proteins, it is perhaps surprising that there is no universally applicable, absolute method to quantify protein concentration. The methods in common use are relative methods, their result is influenced by the amino acid composition of the protein in question. Quantitation is usually obtained by comparison of the signal with that of a reference protein. The reference protein should be cheap and easy to obtain in consistent quality, and its signal/concentration ratio should be similar to that of the protein to be analysed. Most commonly used are Bovine serum albumin (BSA) and immunoglobulin. Simply by choice of assay method and standard protein, one can change the resulting protein concentration by a factor of 20! This needs to be kept in mind when interpreting results. The following methods are in common use:
Aromatic amino acids absorb UV-light between 260–290nm, 280nm is most commonly used. The method is simple and does not destroy the sample....
KeywordsAmino Acid Composition Peptide Bond Aromatic Amino Acid Malachite Green Coomassie Brilliant Blue
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