Interfacial Activation Of Immobilized Enzymes In Confined Space And Its Efficient Catalysis In The Synthesis Of 4H-pyrans Drug Intermediates From Non-specific Substrates

Enzyme,well known as an efficient bio-catalyst,exhibits efficient catalytic activity for specific substrates,but low activity for non-specific substrates.Researches on the enzyme structure regulation to realize the efficient catalysis on the non-specific substrates become the hotpot and also the great challenge in the field of the biochemistry,catalysis and so on.Herein,mesoporous silica materials immobilzed Aspergillus niger lipase(ANL)have been prepared to catalyze non-specific substrates to efficiently synthesize 4-H pyran drug intermediate through the interfacial activation effect in confined space.Through tailoring the pore structure(pore shape and pore size)and surface property of the mesoporous silica to control the geometrical and chemical microenvironments of the immobilized ANL,the interfacial activation effect in confined space has been investigated in detail.The main research work is displayed as follows:1.Mesoporous SBA-15 material with a two-dimensional hexagonal pore structure and mesoporous MCF material with a three-dimensional cage-like pore structure were first employed to prepared immobilized ANL catalysts.The pore size for the two supports was controlled at?11 nm to prepare SBA-15-11-ANL and MCF-11-ANL catalysts.In the synthesis of 4-H pyranoids from non-specific substrates,SBA-15-11-ANL(174.6 U·g-1)and MCF-11-ANL(246.9 U·g-1)both exhibit superior activity to that for the pristine ANL(64.2 U·g-1).The fluorescence spectrum and ATR-FTIR spectrum characterizations of the immobilized ANL indicates the mesopores with three-dimensional cage-like pore structure exhibits stronger interfacial activation effect.2.Tailoring the pore size of the three-dimensional cage-like mesopore into 8,23,and 31 nm,the interfacial activation effect has been investigated in detail.It is found that the the interfacial activation effect depends on the pore size in the synthesis of 4-H pyranoids from non-specific substrates.Along with the increase of the pore size,the activity reaches a maximum value at the pore size of 11 nm(SBA-15-11-ANL).The fluorescence spectra indicate SBA-15-11-ANL possesses the strongest polarity of the Trp microenvironment.ATR-FTIR spectrum reveals the SBA-15-11-ANL exhibits the greatest increase of ?-helix content and decrease of ?-turn content.Moreover,the possible mechanim on the change of the amino acid active site has been proposed.3.Through changing the hydrophobic chain length of the modified agents on the MCF,the chemical microenvironment of the MCF-23 surface has been tailored(MCF-23-CH3,MCF-23-(CH2)2CH3,MCF-23-(CH2)8CH3,MCF-23-(CH2)11CH3,MCF-23-(CH2)18CH3).In the synthesis of 4-H pyranoids from non-specific substrates,compared to the pristine ANL(183.3 U·g-1),the catalytic activity of immobilized ANL exhibits a increase and then a decrease along with the surface hydrophobicity and reaches a maximum of 233.7 U g-1 for MCF-23-CH3-ANL.4.The recycling of the immobilized ANL and the tolerance of the non-specific substrates have been also investigated.For MCF-23-ANL,the catalytic activity maintains 72%of the initial activity after 5 runs.