Reaction pathway and mechanism for Gly-Gly and Ala-Ala under pulsed arc discharge on argon-water interface

Peptides are molecules having amino acid polymer structure, and are being used as health supplements, pharmaceutical products and sweeteners. In general, they are synthesized by using a condensing agent and enzymes. However, this conventional method has some drawbacks such as the need for a long reaction time and formation of large amounts of byproducts and wastes. To resolve this problem, this study aims to synthesize peptides by pulse discharge plasma under catalyst-free condition. Results showed that using alanylalanine (Ala-Ala) and glycylglycine (Ala-Gly) as raw materials, elongation reaction proceeded by the pulsed discharge at argon-water interface. Formation of oligomers was observed, while decomposition and addition products were also present. The reaction pathway was also elucidated from the obtained products.