DETERMINATION OF THE PATTERN OF METHYL ESTERIFICATION IN PECTIN - DISTRIBUTION OF CONTIGUOUS NONESTERIFIED RESIDUES

A method is described for determining the distribution of contiguous n onesterified galacturonic acid residues within pectins. First, the est erified galacturonic acids are converted to galactose by reduction wit h sodium borohydride, then the glycosidic linkages of the resulting ga lactose residues are cleaved selectively by liquid HF solvolysis. Sepa ration and quantitation of the resulting galacturonic acid containing oligomers reveals the proportion of each stretch of contiguous noneste rified galacturonic acid residues in the original pectin. The distribu tion of nonesterified GalA in a pectin fraction obtained from cotton s uspension culture cell walls with approximately 50% esterification app ears to be far from random.