Mode of De-esterification of Alkaline and Acidic Pectin Methyl Esterases at Different pH Conditions

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 (pI) and an acidic pH optimum and by a plant PME that was characterized by an alkaline pI and an alkaline pH optimum. Interchain and intrachain...

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Veröffentlicht in:Journal of agricultural and food chemistry 2006-10, Vol.54 (20), p.7825-7831
Hauptverfasser: Duvetter, Thomas, Fraeye, Ilse, Sila, Daniel N, Verlent, Isabel, Smout, Chantal, Hendrickx, Marc, Van Loey, Ann
Format: Artikel
Sprache:eng
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Zusammenfassung: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 (pI) and an acidic pH optimum and by a plant PME that was characterized by an alkaline pI 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. Keywords: Pectin methyl esterase; mode of action; effect of pH; effect of pI
ISSN:0021-8561
1520-5118
DOI:10.1021/jf060013h