Submitted to: Oklahoma Academy of Science Proceedings
Publication Type: Abstract Only
Publication Acceptance Date: 12/15/1997
Publication Date: N/A
Technical Abstract: Peroxidase has been implicated in suberization, lignification, wound healing and disease resistance in plants. The cantaloupe exocarp is the first defense against fruit rot pathogens. According to nitrocellulose blots of cantaloupe fruit, peroxidases were located in exocarp and mesocarp tested at every stage of development. However, an increase in exocarp peroxidase was observed in 15 to 50 day old fruit. Total peroxidase activity of exocarp tissue peaked in 30-day fruit. IEF-PAGE and Native- PAGE indicated a shift in isoforms from anionic to cationic as the fruit matured. Cationic and anionic isoforms were purified using acetone protein extraction, ion-exchange chromatography, and size- exclusion chromatography. Ion-exchange chromatography revealed 2 cationic and 2 anionic peaks of peroxidase activity. Cationic and anionic peroxidases have an apparent native molecular weight range of 17-28 kD. SDS-PAGE of cationic peroxidases indicated two isoforms with molecular weights of ca. 37 and 52 kD, anionic peroxidases were 32 and 41 kD. Cationic isoforms appeared to more stable and more abundant than anionic peroxidases in the exocarp.