Abstract Protepsin belongs to the class of acid proteinases, containing carboxyl groups in the active center. The preparation cleaves peptide bonds formed by aromatic amino acids (tyrosine, phenylalanine), and does not hydrolize esters and amides. Along with the proteolytic complex, Protepsin contains collagenase, lipase, and other digestive enzymes. The preparation is obtained according to the original technology through maceration of animal endocrine raw materials, followed by purification, concentration, isolation and freeze dehydration of the enzyme complex. The results of the laboratory studies of the proteolytic activity of enzyme preparations show that Protepsin, the preparation of animal origin with a proteolytic activity of 100 units/g, has the greatest collagenase activity in the biomodification of native collagen-containing raw materials.