title: Separation of thermostable pectinmethylesterase from marsh grapefruit pulp.
abstract: A rapid, ion-exchange method that isolates thermostable pectinmethylesterase (TS-PME) from Marsh grapefruit pulp is presented. TS-PME was selectively extracted with 1 M NaCl and equilibrated at low pH (3.1 +/- 0.04). After dilution to a final concentration of 50 mM acetate buffer, pH 5.5, and 0.1, 0.25, or 0.5 M NaCl, the extract was applied to an ion-exchange column without ammonium sulfate precipitation and dialysis. The percent yield varied from an average of 70% (0.1 M NaCl) to 14% (0.5 M NaCl), with a specific activity of >400 U/mg protein in the latter sample. TS-PME activity of some column fractions varied compared with crude extracts before column separation. Some fractions lost thermostability after separation if loaded at 0.1 M or 0.25 M NaCl. In extracts that were loaded at 0.5 M NaCl, the TS-PME activity was significantly higher than that observed in the heated crude extracts. Ion-exchange chromatography may have separated an unidentified protective factor in PME fractions.
authors.affiliation: Department of Food Science and Technology, University of Georgia, Athens, Georgia 30602, USA.
authors.forename: M
authors.initials: M
authors.lastname: Corredig
authors.forename: W
authors.initials: W
authors.lastname: Kerr
authors.forename: L
authors.initials: L
authors.lastname: Wicker
mesh_terms: D002265:Carboxylic Ester Hydrolases / Q000302:isolation & purification*; D002852:Chromatography, Ion Exchange; D002957:Citrus / Q000201:enzymology*; D006863:Hydrogen-Ion Concentration
chemical_list: D002265:Carboxylic Ester Hydrolases; C022323:pectinesterase