Descriptive parameters for revealing substitution patterns of sugar beet pectins using pectolytic enzymes

Enzymatic fingerprinting was applied to sugar beet pectins (SBPs) modified by either plant or fungal pectin methyl esterases and alkali catalyzed de-esterification to reveal the ester distributions over the pectin backbone. A simultaneous pectin lyase (PL) treatment to the commonly used endo-polygalacturonase (endo-PG) degradation showed to be effective in degrading both high and low methylesterified and/or acetylated homogalaturonan regions of SBP simultaneously. Using LC-HILIC-MS/ELSD, we studied in detail all the diagnostic oligomers present, enabling us to discriminate between differently prepared sugar beet pectins having various levels of methylesterification and acetylation. Furthermore, distinction between commercially extracted and de-esterified sugar beet pectin having different patterns of substitution was achieved by using novel descriptive pectin parameters. In addition to DBabs approach for nonmethylesterified sequences degradable by endo-PG, the "degree of hydrolysis" (DHPG) representing all partially saturated methylesterified and/or acetylated galacturonic acid (GalA) moieties was introduced as a new parameter. Consequently, the description DHPL has been introduced to quantify all esterified unsaturated GalA oligomers.