RESEARCH METHODOLOGY OF SUS SCROFA TISSUE EXTRACTS PROTEIN-PEPTIDE COMPONENTS

Abstract

The article presents a comparative analysis of four methods for quantifying the protein-peptide complexes content in extracts obtained from animal raw materials, as well as the low- and highmolecular weight extract fractions: the direct spectrophotometric determination at wavelengths of 260 and 280 nm with subsequent calculation by the Kalckar formula; the biuret reaction by the Kingsley-Weichselbaum method; the method with Bradford reagent and the standard Lowry method. Experimental data analysis demonstrates that in case of the extract that contains protein-peptidic complexes in different molecular weights range, the Kingsley-Weichselbaum method shows the highest quality of protein concentration determination; while studying highmolecular weight fraction (more than 30 kDa), it is possible to obtain more information by combining the spectrophotometric method and the Kingsley-Weichselbaum method. Low-molecular weight fractions (less than 30 kD) should be investigated by complex methods including the spectrophotometric method, Lowry and Bradford methods. These methods make it possible to presumably estimate protein molecules size ranges (by amount of peptide bonds), and also to determine hydrophobic and aromatic amino acids presence.

Keywords

• proteins
• peptides
• extraction
• spectrophotometry
• bradford assay
• lowry’s assay
• kingsley-weixelbaum assay
• biuret reaction