Author:

Keywords:

pectin methyl esterase, mode of action, effect of ph, effect of pl, high-pressure treatment, aspergillus-niger, methylesterase inhibitor, nmr-spectroscopy, methoxyl pectin, action patterns, lime pectins, apple pectin, pectinesterase, endopolygalacturonase, Science & Technology, Life Sciences & Biomedicine, Physical Sciences, Agriculture, Multidisciplinary, Chemistry, Applied, Food Science & Technology, Agriculture, Chemistry, effect of pH, HIGH-PRESSURE TREATMENT, ASPERGILLUS-NIGER, METHYLESTERASE INHIBITOR, NMR-SPECTROSCOPY, METHOXYL PECTIN, ACTION PATTERNS, LIME PECTINS, APPLE PECTIN, PECTINESTERASE, ENDOPOLYGALACTURONASE, Aspergillus, Carboxylic Ester Hydrolases, Citrus, Esterification, Hydrogen-Ion Concentration, Solanum lycopersicum, Pectins, Recombinant Proteins, 03 Chemical Sciences, 07 Agricultural and Veterinary Sciences, 09 Engineering, Food Science, 30 Agricultural, veterinary and food sciences, 34 Chemical sciences, 40 Engineering

Abstract:

Highly esterified citrus pectin was de-esterified at pH 4.5 and 8.0 by a fungal pectin methyl esterase ( PME) that was shown to have an acidic isoelectric pH ( p I) and an acidic pH optimum and by a plant PME that was characterized by an alkaline p I and an alkaline pH optimum. Interchain and intrachain de-esterification patterns were studied by digestion of the pectin products with endo-polygalacturonase and subsequent analysis using size exclusion and anion-exchange chromatography. No effect of pH was observed on the de-esterification mode of either of the two enzymes. Acidic, fungal PME converted pectin according to a multiple-chain mechanism, with a limited degree of multiple attack at the intrachain level, both at pH 4.5 and at pH 8.0. A multiple-attack mechanism, with a high degree of multiple attack, was more appropriate to describe the action mode of alkaline, plant PME, both at pH 4.5 and at pH 8.0.