Isolation and Fundamental Properties of endo-Pectate Lyase pl-Isozymes from Erwinia carotovora†

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Abstract
A strain of Erwinia carotovora was found to produce extracellularly four kinds of endo-pectate lyase pl-isozyme (PATE-I, -II, -III and -IV) having similar properties. The four pl-isozymes were purified to homogenous states by ion exchange chromatography, gel filtration and isoelectric focusing. The approximate molecular weights were 28,000 for PATE-I and -III, 32,000 for PATE-II and 33,000 for PATE-IV, respectively, and they had isoelectric points of 10~11. The optimum pHs for the reaction catalyzed by these pl-isozymes were 9.3 for PATE-II, 9.5 for PATE-IV and 9.7 for PATE-I and III, respectively. There were no differences in the optimum Ca2+ concentration (0.5~0.6 mM) or Km and Vmax among these four pl-isozymes. The mode of action of all the pl-isozymes was determined to be the endo-type.