On the action of ozone on proteins

Five different proteins, invertase, pectinase, papain, trypsine and gelatine have been examined in their reactivity with ozone. Electronic spectroscopy has been used to monitor the protein reaction with ozone in solution. It has been found that only cysteine and the aromatic amino acids tryptophan, tyrosine and phenylalanine are oxidized, however the polyamide bond of the protein main chain is not degraded by the action of O-3 as demonstrated both by electronic spectroscopy and viscometric data. In the dry state (as fixed bed) the proteins are not attacked by O-3 even after hours of exposure. In solution, FT-IR spectroscopy is able to show some degree of oxidation of the protein only after prolonged exposure. Polarimetric measurements of the specific optical rotation of proteins have shown that O-3 causes denaturation of the proteins, i.e. introduces changes in their secondary and tertiary structure. It is possible that these changes are connected with the partial oxidation of the aromatic monomeric units of the proteins and/or cysteine units. (C) 2003 Elsevier Ltd. All rights reserved.