Enzymological and immunological properties of pectin lyases from bacteriocinogenic strains of Erwinia carotovora.

Abstract

Pectin lyases of four bacteriocinogenic Erwinia carotovora strains, Er, Ar, Ar13 and 6083, were purified to near homogeneity from cultures treated with mitomycin C. Pectin lyases from these strains had similar molecular weights of around 28, 000, and their optimal pH for reaction was about 8.0. All these enzymes cleaved a highly methylesterified polygalacturonic acid (90% esterified) well, but with pectin (64% esterified) they showed reduced activities. They did not attack polygalacturonic acid which was not esterified. In contrast to these similarities, the isoelectric points of the enzymes were slightly different from each other, ranging between pI 9.55 and 9.62, and suggests that these enzymes were not identical protein molecules. Antiserum against the pectin lyase of strain Er similarly inactivated the pectin lyases of the other strains, as well as the pectin lyase of strain Er. No immunoprecipitate line was formed between the antiserum against pectin lyase of strain Er and polygalacturonic acid (pectate) lyase of this strain or between antiserum against pectate lyase of strain Er and pectin lyases of the four strains. Antiserum against carotovoricin from strain Er neutralized carotovoricins from strains Er, Ar, Arl3 and 6083 to a similar extent. These results imply that these pectin lyases share a common genetic background and that these carotovoricins might be derived from the same source.