FIGURE 5.
Capillary electrophoresis of EndoHf-digested partly de-methyl-esterified pectin. A, CE of apple pectin samples digested with EndoPG II and run with 50 mm background electrolyte at 20 kV applied voltage. Highly methyl-esterified apple pectin has first been treated with strong base (labeled Base), Csi-PME, or Ani-PME2 to a constant degree of methylesterification of ∼35%. EndoPG II digestion of the de-methyl-esterified sample obtained by using Csi-PME produces only mono-, di-, and tri-galacturonic acid fragments of upon digestion with EndoPG II. For the base-generated and Ani-PME2-treated substrate, both of similar DM, however, many more fragments (see dotted boxes) can be identified as being partially methyl-esterified oligogalacturonides, consistent with the more random placement of the unmethyl-esterified residues by base or Ani-PME2. B, capillary electrophoresis of EndoHf-digested partly de-methyl-esterified pectin. CE of apple pectin samples digested with EndoPG II and run with 100 mm phosphate running buffer at 30 kV applied voltage. Highly methyl-esterified apple pectin was first treated with strong base (labeled Base) or glycosylated Ani-PME2, or Ani-PME1 to a constant degree of methylesterification of ∼40%. Unmethyl-esterified peaks are labeled, and additional peaks corresponding to methyl-esterified fragments appearing in all three digests are indicated by dotted lines (101).