Purification, biochemical characterization and cloning of a new cationic peroxidase isoenzyme from artichoke

A cationic soluble peroxidase isoenzyme (CysPrx) has been purified and characterized from artichoke (Cynara cardunculus subsp. scolymus (L) Hegi) leaves by combination of aqueous two phase extraction, ion exchange chromatography, and gel filtration. The purification fold was 149 and the activity recovery 5.5%. CysPrx was stable from 5 to 45 C with a pH optimum around 5.5; the pl was 8.3 and the MW of 37.7 +/- 1.5 kDa. MALDI-TOF MS analysis provided partial peptide sequences and resolved CysPrx isoenzyme into two putative isoforms. The presence of these isoforms was confirmed by the isolation of full-length cDNA encoding CysPrx that generate two slightly different sequences coding for two putative CysPrx: CysPrx1 and CysPrx2. The obtained MS peptides showed a 35% coverage with 100% identity with the two CysPrx deduced protein sequences. A molecular modeling analysis was carried out to predict in silico the protein structure and compare it with other plant Prx structures. Considering that CysPrx is quite stable, the study carried out in this paper will offer new insights for the production of the recombinant protein for utilization of CysPrx as an alternative Prx for food technology, biomedical analysis and bioremediation. (C) 2011 Elsevier Masson SAS. All rights reserved.