Partially deacetylated chitin as an acid-stable support for enzyme immobilization

Partially deacetylated chitin (PDAC) obtained by boiling chitin in 28.6% (w/w) sodium hydroxide was not dissolved when it was suspended in 2% acetic acid (pH 2.6) at 60°C for 12 h or autoclaved in acetate buffer (pH 5.0) for 20 min. The enzyme binding ability of the PDAC with glutaraldehyde was similar to that of chitosan. Immobilized pullulanase had low enzyme activity for high-molecular-weight material such as pullulan, but its activity for maltosyl β-cyclodextrin was almost the same as that of the free enzyme. The immobilized enzyme produced branched cyclodextrin through a reverse reaction in acetate buffer of pH 3.75 at 53°C.