Pectins and pectolytic enzymes in relation to development and processing of green beans (Phaseolus vulgaris L.)

Abstract Processing of green beans involves major changes within the composition of cell wall pectins. About 20% of homogalacturonan is degraded while 65% of rhamnogalacturonan is solubilized. Since β-eliminative breakdown, which is dependant on the degree of pectin methylesterification, is probably the main mechanism explaining this phenomenon, a biochemical and molecular biological study was initiated on the cell wall enzyme pectin methylesterase [PE]. Two groups of isoenzymes with molecular weights of 33 kDa and 42 kDa and different thermostabilities were partly purified. In addition, it appeared that two PE genes, most likely encoding precursor proteins of 63 kDa, are expressed during pod development.