[Need-related availability of short-chain peptides--a prerequisite for their use in artificial feeding].

The present knowledge about extraintestinal peptide assimilation opens now for the first time the possibility to formulate "complete and well-balanced" as well as "tailored" amino acid solutions by using short-chain peptides. A prerequisite for a commercial production of such amino acid/peptide preparations to be used in parenteral nutrition is, however, an adequate provision of suitable synthetic peptides in industrial scale. By applying the N-carboxy-anhydride method we have synthesized various glutamine-, tyrosine- and cystine-containing peptides in high yields. The dipeptide L-alanyl-L-glutamine as well as the tripeptides bis-L-tyrosinyl-L-lysine, bis-glycyl-L-cystine and bis-L-alanyl-L-cystine exhibit high chemical and optical purity, excellent solubility in water and stability during heat sterilization and storage thereby complying with all chemical/physical criteria for substrates in clinical nutrition. In the frame of our biotechnological research, we successfully applied proteases of plant, animal or microbial origin for the synthesis of various glutamine- and cyst(e)ine-containing peptides. Compared with chemical methods, this enzyme-catalyzed peptide synthesis offers certain advantages, especially the (stereo-)specificity of the reaction, short reaction times as well as simple purification procedures. The use of immobilized biocatalysts facilitates the development of a rational and economic method for an adequate provision of short-chain peptides in industrial scale.