Transesterification of insoluble polysaccharides

US6228997A · kind A · utility

Assignee

• The United States of America as represented by the Secretary of the Army · US

Inventors

• Joseph A. Akkara · Holliston, US
• David L. Kaplan · Seattle, US
• Ferdinando Bruno · Andover, US
• Jonathan S. Dordick · Schenectady, US

Key dates

• Filing date: Jul 10, 1998
• Grant date: May 8, 2001
• Expiry date: Jul 10, 2018

Classification

• Technology area (CPC C): Chemistry; Metallurgy
• CPC primary: C12P19/04
• WIPO field: Macromolecular chemistry, polymers
• WIPO sector: Chemistry

Abstract

Bacillus subtilis protease catalyzes the acylation of organic solvent-insoluble polysaccharides in isooctane solution containing vinyl esters of fatty acids as acyl donor. The reaction occurs only when the enzyme is solubilized via ion-pairing with the anionic surfactant dioctyl sulfosuccinate, sodium salt (AOT). Enzyme based acylation was demonstrated with amylose, cyclodextrins, cellulose, cellulose derivatives, and other polysaccharides such as chitosan, pullulan, and maltodextrose. These polysaccharides are reactive either as a cryogenically milled powder suspended in the organic solvent or as a thin film deposited onto ZnSe slides. For chitosan, .alpha.-cyclodextrin, and hydroxyethyl cellulose (HEC), the enzymatic crosslinking reaction occurs using adipic acid divinyl ester (C6DVE). HEC forms a compound that gels in solvents such as ethyl alcohol and dimethyl sulfone oxide (DMSO). Electron spectroscopy chemical analysis (ESCA) of the first 100 .ANG. of the amylose thin film amylose indicates that the acylated surface had a degree of substitution of 0.9.+-.0.1 acyl chains per glucose moiety and this corresponded well to the expected regioselectivity of subtilisin catalysis on g…