In the course of analyzing the partial amino acid sequences of Cry j I, a major allergen of Japanese cedar (Cryptomeria japonica) pollen, we found a peptide fragment which has a significant homology to some pectate lyase isozymes secreted by plant pathogenic bacteria. Therefore, we investigated whether Cry j I has pectate lyase activity. Cry j I reacted with polygalacturonic acid, resulting in the release of unsaturated uronide products. The optimum temperature and pH for the reaction were 60-70 degrees C and pH 10. The enzymatic reaction had an absolute Ca2+ ion requirement. These characteristics were very compatible with the character of the pectate lyase isozymes reported previously. These results clearly show that Cry j I has pectate lyase activity.