Green Synthesis and Physical and Chemical Characterization of Chitosans with a High Degree of Deacetylation, Produced by a Binary Enzyme System  

作　　者：Laidson Paes Gomes Cristina Tristao Andrade Joab Trajano Silva Eduardo Mere Del Aguila Vania Margaret Flosi Paschoalin 

机构地区：[1]Institute of Chemistry, University Federal of Rio de Janeiro, Rio de Janeiro 21941-909, R J, Brazil [2]Institute of Macromolecules Professora Eloisa Mano, University Federal of Rio de Janeiro, Rio de Janeiro 21945-598, R J, Brazil

出　　处：《Journal of Life Sciences》2014年第3期276-282,共7页生命科学（英文版）

摘　　要：Chitosan is a biopolymer obtained from chitin, where the N-acetylglucosamine monomer is in its deacetylated form; this polymer is useful for a wide variety of industrial applications. The properties and uses of chitosan depend on its physical and chemical characteristics, which result from the treatments used for its production. In this study, we report the preparation and characterization ofchitosan oligosaccharides by a green synthesis from crystalline shrimp chitin, using a sequential enzyme treatment by chitinase and chitin deacetylase. Chitinases were purified from grapes and used to rupture the crystalline shrimp chitin structure, modifying the crystallinity index from 57.6% to 15.9%. The resultant polymers were deacetylated using a recombinant chitin deacetylase from Saccharomyces cerevisiae, which was cloned and expressed in Pichia pastoris. The chitosans produced showed an estimated DA （degree of acetylation） of approximately 20%, and the molecular weights ranged from -7,600 to -3,700 after treatment in pH 3.0 and pH 6.0 for 10 min and 40 min, respectively. Physical and chemical characterization of the products indicated that enzyme fragmentation of chitin probably makes the acetamide groups more accessible to deacetylation, forming homogeneous polymers that are free of hazardous sub-products, have defined low molecular weights, and are highly deacetylated.

关 键 词：CHITOSAN binary enzyme system CHITINASES recombinant chitin deacetylase low acetylation degree low molecular weight. 

分 类 号：O636.1[理学—高分子化学] O613.71[理学—化学]