VIEW ARTICLE

Physiology and Biochemistry

Purification and Characterization of Cutinase from Venturia inaequalis. Wolfram Köller, Assistant professor, Department of Plant Pathology, Cornell University, New York State Agricultural Experiment Station, Geneva 14456; Diana M. Parker, Research assistant, Department of Plant Pathology, Cornell University, New York State Agricultural Experiment Station, Geneva 14456 Phytopathology 79:278-283. Accepted for publication 16 August 1988. Copyright 1989 The American Phytopathological Society. DOI: 10.1094/Phyto-79-278.

Venturia inaequalis was grown in a culture medium containing purified apple cutin as the sole carbon source. After 8 wk of growth an esterase was isolated from the culture fluid and purified to apparent homogeneity. The enzyme hydrolyzed tritiated cutin and thus was identified as cutinase. The purified cutinase is a glycoprotein with a molecular mass of 21–23 kg/mol, as determined by various procedures. Remarkable structural features are a high content of glycine, a high content of nonpolar amino acids, two disulfide bridges, and a high degree of hydrophobicity. Cutin hydrolysis by cutinase from V. inaequalis is optimal at a pH of 6 and thus different from the alkaline pH-optimum reported for other purified cutinases. The hydrolysis of the model ester p-nitrophenyl butyrate was less affected by the pH. The esterase activity was strongly inhibited by diisopropyl fluorophosphate, and the phosphorylation of one serine was sufficient for complete inhibition. Thus, cutinase from V. inaequalis belongs to the class of serine hydrolases, a characterisitic shared with other fungal cutinases.