Die Verteilung der freien und veresterten Carboxylgruppen im Pektinmolekül nach Einwirkung von Pektinesterase ausAspergillus niger und Orangen
✍ Scribed by Kohn, R. ;Dongowski, G. ;Bock, W.
- Publisher
- John Wiley and Sons
- Year
- 1985
- Tongue
- English
- Weight
- 647 KB
- Volume
- 29
- Category
- Article
- ISSN
- 0027-769X
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✦ Synopsis
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.