Artificial chaperoning of insulin, human carbonic anhydrase and hen egg lysozyme using linear dextrin chains – a sweet route to the native state of globular proteins

Abstract

Linear dextrins (α-1,4- d-glucopyranoside chains) are known to possess amphiphilic surfaces and solubilize lipophilic compounds. We have assessed the ability of this amphiphilic surface of dextrin to inhibit the self-aggregation and assist the refolding of proteins. Addition of decameric dextrin, or dextrin-10, in the renaturation buffer improves the refolding yield of human carbonic anhydrase from its guanidinium chloride-induced denatured state. It is also seen to inhibit the self-aggregation of insulin. The ability of dextrin-10 to interact with cetyltrimethylammonium bromide and postpone its critical micellar concentration allows the use of dextrin-10 as a `detergent stripping agent' in a novel artificial chaperoning process described earlier. The aggregation of human carbonic anhydrase and lysozyme upon refolding is prevented by cetyltrimethylammonium bromide due to the formation of a protein-detergent complex; dextrin-10 strips off the detergent from the complex and allow the proteins to fold, thus increasing the renaturation yield. Dextran-4 (the α-1,6- d-glucopyranoside chain), which does not exhibit amphiphilic properties, does not help in such artificial chaperoning.