Combi-metal organic framework (Combi-MOF) of alpha-amylase and glucoamylase for one pot starch hydrolysis

The multi-enzyme biocatalyst allows to run in vitro multi-step cascade reactions in single pot. An efficient combimetal organic frameworks (combi-MOF) of alpha-amylase and glucoamylase for one pot starch hydrolysis was constructed by mixing zinc acetate and 2 methylimmidazole with enzyme mixture in one pot under biocompatible conditions. The prepared combi-MOF was characterized and analyzed by powder X-ray diffraction (PXRD), Fourier transform infrared (FT-IR), thermogravimetric analysis (TGA) and scanning electron microscopy (SEM). Thermo-stability was evaluated for combi-MOF in the range of 55 to 75 degrees C which showed three folds improved stability in terms of half-life. In kinetic parameter studies, rate of starch hydrolysis (V-max) of combi-MOF was found to be enhanced after co-immobilization. Further, combi-MOF was recycled in batch mode which retained up to 52% residual activity after five successive cycles of reuse. In addition to that, combi-MOF exhibited extraordinary storage stability till 24 days. At the end, starch hydrolytic activity of combi-MOF was tested for different sources of starch (corn, rice, wheat and potato) which exhibited higher rate of hydrolysis than mixture of free enzymes due to spatially co-localized multi-enzymatic systems. (C) 2018 Elsevier B.V. All rights reserved.