Enzyme Aided Analysis of the Substituent Distribution along the Chain of Cellulose Acetates Regioselectively Modified by the Action of an Aspergillus niger Acetylesterase

Two cellulose acetates (CA) were regioselectively deacetylated by action of a pure Aspergillus niger acetylesterase from the carbohydrate esterase family 1. The action of acetyl esterase along the polymeric chain was monitored by a new enzyme-aided method. CA with and without esterase modification was hydrolysed with a pure endoglucanase. The fragments were deutero-acetylated and separated by preparative SEC in CHCl₃. The partial degree of substitution of the individual fragments was determined by ¹H-NMR spectroscopy. The investigation confirmed the uniform regioselective and regular deacetylation along the polysaccharide chain. The partial substitution in C₂ seemed to be of major importance for the enzyme's mode of action.