TITLE	Purification and characterization of a pectin lyase from Pythium splendens infected cucumber fruits
AUTHOR	Wei-Chen Chen Department of Plant Pathology and Entomology, National Taiwan University, Taipei, Taiwan, Republic of China Huann-Ju Hsieh Department of Plant Pathology and Entomology, National Taiwan University, Taipei, Taiwan, Republic of China Tsung-Che Tseng Institute of Botany, Academia Sinica, Nankang, Taipei, Taiwan, Republic of China
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ABSTRACT	A pectin lyase (PL, EC 4.2.2.10) was produced by Pythium splendens Braun in infected cucumber fruits. The enzyme was purified to near homogeneity by ammonium sulfate fractionation, CM - Sepharose column chromatography, and preparative isoelectric focusing. The enzyme had a molecular mass of 23 kDa as determined by SDS-PAGE. The pI of the PL was 8.0, which was also the optimum pH for the enzyme activity. The enzyme was stable at 4_50°C, but beyond 50°C, its activity decreased rapidly. The pectin lyase degraded high methyl-esterified pectin by trans-elimination in an endo-manner, and was stimulated by some divalent cations including Ca2+, Mg2+, and Sr2+. Addition of Zn2+ inhibited the enzyme activity by 36%. The purified PL caused rapid maceration of potato and cucumber discs. This is the first report of a PL produced by Pythium splendens, a plant pathogenic fungus which causes seedling damping-off and fruit rot in cucumber.
KEYWORD	Cucumber (Cucumis sativa L.); Pectin lyase; Pythium splendens;
ARTICLE INFO	Botanical Bulletin of Academia Sinica, Volume 39 Number 3 July 1998, page 181-186, 6 pages
PUBLISHER	Institute of Plant and Microbial Biology, Academia Sinica, Taipei, Taiwan, Republic of China