Enzymatic degradation of chitins and partially deacetylated chitins.

The enzymatic (lysozyme, chitinase etc.) digestibility of chitins obtained from squid pen and shrimp shell, and of partially deacetylated chitins (DA-chitins) was investigated. The digestibility of various chitins by the chitinase from Bacillus sp. PI-7S was much higher than that by lysozyme, and beta-chitin was digested more smoothly than alpha-chitin. DA-chitin deacetylated under homogeneous conditions (DAC) was hydrolysed by lysozyme more rapidly than that deacetylated under heterogeneous conditions (DAC). DACs from shrimp shell and squid pen showed the same degree of digestibility by lysozyme in spite of a difference in the crystal structure of the original chitins. The crystal structure of chitin and the degree of N-acetyl group aggregation among DA-chitin molecules affect the enzymatic digestibility of chitin and DA-chitin, respectively.