Purification and catalytic properties of polygalacturonase isoforms from ripe avocado (Persea americana) fruit mesocarp.
Endo-polygalacturonase (PG; EC 3.2.1.15) was recovered from the cell walls of avocado mesocarp (Persea americana Mill cv. Lula) tissue and purified by sequential ion exchange and gel permeation chromatography. Two isoforms (S-I and S-II) were recovered, exhibiting molecular masses of about 41 kD on size exclusion media and about 48 (S-I) and 46 (S-II) kDa as determined by sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE). Both isoforms exhibited maximum activity at pH 6.0 against polygalacturonic acid (PGA) and hydrolyzed PGA of about 180 kDa to polymers of about 4 kDa. The catalytic activity of the 48-kDa isoform against PGA was slightly higher than that of the 46-kDa isoform. The purified PGs catalyzed significant molecular mass downshifts in the polyuronides of pre-ripe avocados; however, the capacity of the enzymes to solubilize polyuronides from cell walls of pre-ripe fruit was limited.
Wakabayashi
Kazuyuki
K
Department of Biology, Faculty of Science, Osaka City University, Sumiyoshi-ku, Osaka 558-8585, Japan Horticultural Sciences Department, Institute of Food and Agricultural Sciences, PO Box 110 690, University of Florida, Gainesville, FL 32611, USA.
Huber
Donald J.
DJ