Abstract
This thesis focuses on the elaboration of appropriate methodical approach for the study of protein phosphorylation, particularly phosphorylation of human pepsins, which are characteriz¬ed by a very low content of basic amino acid residues and a higher content. of acidic amino acid residues. The attention was paid to the elaboration of affinity chromatography methods for the selective separation of phosphorylated pepsins and for the isolation of phosphopeptides derived from these proteins.