Аннотация:Enzyme cost is one of the crucial factors in economically feasible production of second generation biofuels. Finding more active enzymes and lowering the protein dosage may notably reduce the final product cost. When comparing hydrolytic performance of different enzymes or their mixes, the precise monitoring of protein loading becomes very important. Using 12 samples of desalted and freeze-dried cellulases and hemicellulases, purified from different fungi, a comparison of three methods for measuring a protein concentration (Lowry, BCA and that based on A280 measurements) in enzyme solutions prepared from the powders was carried out. Protein concentrations determined by the Lowry and BCA assays were 2% and 10% greater, on average, than real concentrations of dry matter in enzyme solutions. Those measured by the A280 assay, based on a theoretical specific absorption of an enzyme, predicted by the ProtParam tool, were 18% lower, on average, than the concentrations of dry matter in the samples. The apparent underestimations of the latter method could be caused by the presence of covalently bound glycans in the enzyme molecules as well as by other non-protein components in the samples. The use of A280 assay may be recommended for those enzymes, whose amino acid sequences are known.