Silk fibroin hydroxyapatite composite thermal stabilisation of carbonic anhydrase

Abstract

Carbonic anhydrase was entrapped in a matrix of ultrasonically bonded hydroxyapatite microparticles coated with β-sheet structured silk fibroin. Transfer of the reactant and product between the enzyme and the assembly surface was evident and the system showed a remarkable operational, storage and thermal stability, with enzymatic activity almost unchanged after a one hour's treatment at 110 °C and the assembly retained 45% of its initial activity after 3 weeks of continuous heating at 80 °C in an amine solution. This thermal stability was excellent compared with described CA immobilization systems and indicates that silk fibroin may limit thermally induced enzyme conformation changes and prevent desorption.