Butyl ferulate was synthesized using a silica-immobilized commercial lipase (Steapsin) in dimethylsulfoxide (DMSO). Lipase-immobilized by surface adsorption onto silica pretreated with 1% glutaraldehyde showed 89% bin...Butyl ferulate was synthesized using a silica-immobilized commercial lipase (Steapsin) in dimethylsulfoxide (DMSO). Lipase-immobilized by surface adsorption onto silica pretreated with 1% glutaraldehyde showed 89% binding of protein. The esterification of butanol (100 mM) and ferulic acid (50 mM) by silica-bound biocatalyst was carried out at 45℃ for 6 h under shaking (120 rpm). The optimization of various reaction conditions like molar concentration of reactants, biocatalyst concentration, reaction time, temperature, addition of molecular sieves, salt ions, and repetitive bio-catalysis in DMSO were studied, consecutively. The bound lipase (15 mg/ml) catalyzed the esterification of ferulic acid and butanol with a yield of 64 mM under optimized reaction conditions. Among the salt ions Cu2+, Zn2+ and Al3+ ions moderately promoted the ester yield (66 mM) while Mg2+, NH4+, Fe2+ and Ca2+ were found to decrease the ester yield. The by-product (H2O) produced in the reaction was scavenged by the molecular sieves (10 mg/ml) added to the reaction mixture, which enhanced the formation of ester up to 74 mM. During the repetitive reactions, the bound lipase produced 32 mM ester after 4th cycle of esterification. On scaling-up the reaction volume to 30 ml, 32.5 mM butyl ferulate was synthesized under optimized conditions.展开更多
Cholesterol oxidase (COX), a bi-functional FAD-containing microbial enzyme belongs to the family oxidoreductases. COX catalyses the oxidation of cholesterol into 4-cholesten-3-one. In recent time, cholesterol oxidase ...Cholesterol oxidase (COX), a bi-functional FAD-containing microbial enzyme belongs to the family oxidoreductases. COX catalyses the oxidation of cholesterol into 4-cholesten-3-one. In recent time, cholesterol oxidase has received great attention due to its wider use in clinical (determination of serum cholesterol) laboratories practice and in the biocatalysis for the production of a number of steroids. COX has been shown to possess potent insecticidal activity, besides its use to track cell cholesterol. Moreover, COX is also implicated in the manifestation of some of the diseases of bacterial (tuberculosis), viral (HIV) and non-viral prion origin (Alzheimer's). These applications and disease mechanisms have promoted the need of screening, isolation and characterization of newer microbes from diverse habitats as a source of COX to learn more about its structural and functional aspects. In this review, we discuss microbial sources of COX, its structure and important biochemical properties besides its broad range of biological functions and applications.展开更多
文摘Butyl ferulate was synthesized using a silica-immobilized commercial lipase (Steapsin) in dimethylsulfoxide (DMSO). Lipase-immobilized by surface adsorption onto silica pretreated with 1% glutaraldehyde showed 89% binding of protein. The esterification of butanol (100 mM) and ferulic acid (50 mM) by silica-bound biocatalyst was carried out at 45℃ for 6 h under shaking (120 rpm). The optimization of various reaction conditions like molar concentration of reactants, biocatalyst concentration, reaction time, temperature, addition of molecular sieves, salt ions, and repetitive bio-catalysis in DMSO were studied, consecutively. The bound lipase (15 mg/ml) catalyzed the esterification of ferulic acid and butanol with a yield of 64 mM under optimized reaction conditions. Among the salt ions Cu2+, Zn2+ and Al3+ ions moderately promoted the ester yield (66 mM) while Mg2+, NH4+, Fe2+ and Ca2+ were found to decrease the ester yield. The by-product (H2O) produced in the reaction was scavenged by the molecular sieves (10 mg/ml) added to the reaction mixture, which enhanced the formation of ester up to 74 mM. During the repetitive reactions, the bound lipase produced 32 mM ester after 4th cycle of esterification. On scaling-up the reaction volume to 30 ml, 32.5 mM butyl ferulate was synthesized under optimized conditions.
文摘Cholesterol oxidase (COX), a bi-functional FAD-containing microbial enzyme belongs to the family oxidoreductases. COX catalyses the oxidation of cholesterol into 4-cholesten-3-one. In recent time, cholesterol oxidase has received great attention due to its wider use in clinical (determination of serum cholesterol) laboratories practice and in the biocatalysis for the production of a number of steroids. COX has been shown to possess potent insecticidal activity, besides its use to track cell cholesterol. Moreover, COX is also implicated in the manifestation of some of the diseases of bacterial (tuberculosis), viral (HIV) and non-viral prion origin (Alzheimer's). These applications and disease mechanisms have promoted the need of screening, isolation and characterization of newer microbes from diverse habitats as a source of COX to learn more about its structural and functional aspects. In this review, we discuss microbial sources of COX, its structure and important biochemical properties besides its broad range of biological functions and applications.
