title: Action pattern of Valencia orange PME de-esterification of high methoxyl pectin and characterization of modified pectins.
abstract: Valencia pectinmethylesterase (PME) fractions, B-PME, containing 36 and 13 kDa protein bands and U-PME, containing a 36 and 27 kDa protein bands, were used to de-esterify original pectin (O-Pec) from 73% degree of esterification (%DE) to 63% (B-Pec) and 61% DE (U-Pec), respectively. Most O-Pec eluted from ion exchange chromatography at low salt concentration and a smaller component eluted at higher ionic strength. B-Pec and U-Pec eluted as one broad peak at higher ionic strength. PME modification did not change molecular weight: O-pectin (134,000 g/mol), U-Pec (133,850 g/mol), and B-Pec (132,250 g/mol). The NMR signal of GG and GGG increased after modification, whereas the signal of EE and EEE decreased. The negative zeta-potential increased with pH for all pectins. U-PME and B-PME created differently modified pectins that vary in degree and length of multiple attacks and fraction of the pectin population that was modified.
authors.affiliation: USDA ARS Food Quality Unit, Athens, GA, USA.
authors.forename: Yookyung
authors.initials: Y
authors.lastname: Kim
authors.forename: Quincy
authors.initials: Q
authors.lastname: Teng
authors.forename: Louise
authors.initials: L
authors.lastname: Wicker
mesh_terms: D002265:Carboxylic Ester Hydrolases / Q000378:metabolism*; D032084:Citrus sinensis / Q000201:enzymology*; D006863:Hydrogen-Ion Concentration; D007700:Kinetics; D009682:Magnetic Resonance Spectroscopy; D008970:Molecular Weight; D010368:Pectins / Q000737:chemistry* / Q000378:metabolism*; D011199:Potentiometry; D012542:Scattering, Radiation
chemical_list: D010368:Pectins; D002265:Carboxylic Ester Hydrolases; C022323:pectinesterase