Abstract: A chitin deacetylase gene encoding a protein, a plasmid vector containing said gene and a transformant transformed with the plasmid vector. An object of the present invention is to make contribution to the industrial production of said enzyme, by cloning the gene of said enzyme to elucidate the structure of the gene and express the gene.

Abstract: Disclosed is p-nitrophenyl 2-acetylamino-4-O-(2-amino-2-deoxy-.beta.-D-glucopyranosyl)-2-deoxy-.beta. -D-glucopyranoside of formula (1) and its acid-addition salts. ##STR1## The compound of formula (1) is produced by reacting a p-nitrophenyl derivative of chitin dimer with a microorganism-derived deacetylase. The compound and its salts do not act on exo-type chitinases, and are specific to only endo-type ones.

Abstract: Di-N-acetyl-D-chitobiose, which is easily available as a chitin decomposate or a chemical reagent, is reacted with a microorganisms-derived deacetylase to produce 2-acetylamino-4-O-(2-amino-2-deoxy-.beta.-D-glucopyranosyl)-2-deoxy-D-gluc ose of formula (1). ##STR1## The method is quantitative and efficiently produces the compound (1). The compound (1) and its salts are usable as substrates for measuring enzymatic activities, and also as starting substances in the production of various food materials and in the field of glyco-chain engineering.