Recent advances in biochemistry and molecular biology have revolutionized the biological and chemical sciences. The new discipline of protein engineering has emerged, combining biochemistry, physical/organic chemistry, recombinant DNA technology, structural biology, and biochemical engineering. This has provided new approaches to the basic study of protein structure and function, as well as the opportunity to design and produce proteins with a broad spectrum of industrial and health-related applications. Protein engineering plays important role in the protein crystallography. In this work I would like concentrate on the applications of protein engineerig techniques in a phasing of macromolecules:

• overexpression of the selenomethionyl proteins
• mutagenesis as a tool in preparation of heavy-atom derivatives
• improvement of the crystals quality using protein engineering