Synthesis of a chitosan tetramer derivative, β-d-GlcNAc-(1→4)-β-d-GlcNAc-(1→4)-β-d-GlcNAc-(1→4)-d-GlcN through a partial N-acetylation reaction by chitin deacetylase

We have synthesized β-d-GlcNAc-(1→4)-β-d-GlcNAc-(1→4)-β-d-GlcNAc-(1→4)-d-GlcN (2) through a partial N-acetylation reaction of chitosan tetramer 1 by a chitin deacetylase from Colletotrichum lindemuthianum ATCC 56676. The compound was purified from the mixture of acetylation products of 1 using cation-exchange column chromatography and amine-adsorption column chromatography, and its structure was estimated by 1H NMR and FABMS analyses. The enzymatic reaction allows a regioselectivity that is hard to achieve by chemical N-acetylation.