... Watanabe, T., Kobori, K., Miyashita, K., Fujii, T., Sakai, H.,Uchida, M. & Tanaka, H. (1993) Identification of glutamic acid204 and aspartic acid 200 in chitinase A1 of Bacillus circulans ... residues are proposed on the basis of the observed mutational effects, the pH-dependency of theseeffects, pK a calculations and available structural informa-tion. The results indicate that the pK a of ... )1sugar and by increasing the pK a of the catalytic acid. The hydroxyl group of Tyr214 makes a major contribution to the positioning of the N-acetyl group of the )1sugar.Takentogether, the results...