title: Changes in molecular weight of transacylated pectin catalyzed by tomato and citrus pectinesterases as determined by gel permeation chromatography.
abstract: The changes in molecular masses of pectin in 0.5% pectin-pectinesterase (PE) mixtures (2 units/mL) incubated at various temperatures, pH values, and NaCl levels for 30 min were observed by a Toyopearl TSK HW-65 (F) gel permeation chromatography. The molecular mass of pectin was remarkably increased from 103 to 266 kDa when the incubation temperature of pectin-tomato PE was increased from 25 to 45 degrees C. A further increase in molecular mass was observed when a pectin-citrus PE mixture was incubated at 65 degrees C. The values of pH and NaCl levels were also crucial to the transacylation activity of PEs. Reaction at pH 7.5 with tomato PE and citrus PE remarkably expanded the molecular mass of pectin to 410 and 670 kDa, respectively. The NaCl level of 0.3-0.5 and 0.3 M was favorable for the transacylation reaction of tomato PE and citrus PE, respectively. Only high methoxylpectin was the suitable substrate for PE to conduct the transacylation reaction.
authors.affiliation: Graduate Institute of Food Science and Technology, National Taiwan University, Taipei 10617, Taiwan.
authors.forename: Ching-Wen
authors.initials: CW
authors.lastname: Lee
authors.forename: Ming-Chang
authors.initials: MC
authors.lastname: Wu
authors.forename: Bor-Hon
authors.initials: BH
authors.lastname: Lee
authors.forename: Chii-Ming
authors.initials: CM
authors.lastname: Jiang
authors.forename: Hung-Min
authors.initials: HM
authors.lastname: Chang
mesh_terms: D000215:Acylation; D002265:Carboxylic Ester Hydrolases / Q000378:metabolism*; D002384:Catalysis; D002850:Chromatography, Gel; D002957:Citrus / Q000201:enzymology*; D004951:Esterification; D006863:Hydrogen-Ion Concentration; D018551:Solanum lycopersicum / Q000201:enzymology*; D008970:Molecular Weight; D010368:Pectins / Q000737:chemistry* / Q000378:metabolism*; D012965:Sodium Chloride / Q000008:administration & dosage; D013696:Temperature
chemical_list: D012965:Sodium Chloride; D010368:Pectins; D002265:Carboxylic Ester Hydrolases; C022323:pectinesterase