Partial purification and characterization of pectin methylesterase from green beans (Phaseolus vulgaris L)

Pectin methylesterase (PE) is present in green beans and may have an influence on the texture of green beans after commercial sterilization. Two fractions of PE were partially purified from the pods and the seed hulls of green beans (cv. Odessa). PE-1 and PE-2 had molecular weights of 45 and 29 kD, respectively, under native conditions and of 42 and 33.5 kD under denaturating conditions. PE-1 and PE-2 both contained two isoforms of PE activity with isoelectric points of 8.4 and 9.8 and 10.5 and >11, respectively. The active fractions showed a difference in salt dependency, and PE-2 was less heat stable than PE-1.