[The distribution of free and esterified carboxyl groups within the pectin molecule after the action of pectin esterase from Aspergillus niger and oranges].
By reaction of pectin esterase (PE) from Aspergillus niger and oranges as well as lye, with 95% esterified citrus and apple pectin we prepared series of preparations with degrees of esterification between 35 and 77%. In these partial deesterified pectins the form of distribution of the free and esterified carboxyl groups has been determined from the activity coefficient gamma Ca2+ of the calcium counterions in the solutions of the corresponding calcium pectinates, from the electrostatic free enthalpy delta (Gel/N)KCa of the ion exchange Ca2+----2K+ in these systems as well as from the relative activity of the polygalacturonase reacting with sodium pectinate. The PE from A niger hydrolyzes the esterified carboxyl groups more or less randomly, in a manner similar to the effect of lye on pectin. On the other hand PE from oranges brings about block-like groupings of free carboxyl groups in the pectin molecule. The study revealed different reaction mechanisms of the pectin deesterification by pectin esterases from Aspergillus species and higher plants.
D001234:Aspergillus niger / Q000201:enzymology*; D002118:Calcium / Q000032:analysis; D002264:Carboxylic Acids / Q000032:analysis; D002265:Carboxylic Ester Hydrolases / Q000378:metabolism*; D002957:Citrus / Q000032:analysis*; D010368:Pectins / Q000032:analysis*; D011096:Polygalacturonase / Q000032:analysis; D012972:Sodium Hydroxide; D013816:Thermodynamics
D002264:Carboxylic Acids; D012972:Sodium Hydroxide; D010368:Pectins; D002265:Carboxylic Ester Hydrolases; C022323:pectinesterase; D011096:Polygalacturonase; D002118:Calcium
Die Verteilung der freien und veresterten Carboxylgruppen im Pektinmolekül nach Einwirkung von Pektinesterase aus Aspergillus niger und Orangen.