title: Esterification degree of fructose laurate exerted by Candida antarctica lipase B in organic solvents.
abstract: Sugar esters of fatty acids have many applications as biocompatible and biodegradable emulsifiers, which are determined by their degrees of esterification (DE). Direct esterification of fructose with lauric acid in organic media used commercial immobilized Candida antarctica lipase B (CALB) was investigated for DE. Significant difference of DE was observed between 2-methyl-2-butanol (2M2B) and methyl ethyl ketone (MEK), as di-ester/mono-ester molar ratio of 1.05:1 in 2M2B and 2.79:1 in MEK. Fourier transform infrared (FTIR) spectra showed that the secondary structure of the enzyme binding mono-ester presented distinct difference in 2M2B and MEK. Contents of β-turn and antiparallel β-sheet of CALB in 2M2B were 26.9% and 16.2%, respectively, but 19.1% and 13.2% in MEK. To understand the relationship between the conformational changes and differences of DE, mono-ester and fatty acid were directly employed for synthesis of di-ester. The maximum initial velocity of di-ester synthesis in MEK was 0.59 mmolg(enzyme)(-1)h(-1), which was 2.19-fold as greater as that in 2M2B, indicating that CALB conformation in MEK was preferred for the synthesis of di-ester. These results demonstrated that the conformation of CALB binding mono-ester affected by organic solvents essentially determined DE.
authors: School of Life Science and Biotechnology, Dalian University of Technology, Dalian 116024, China.
authors: Lu
authors: L
authors: Li
authors: School of Life Science and Biotechnology, Dalian University of Technology, Dalian 116024, China.
authors: Fangling
authors: F
authors: Ji
authors: School of Life Science and Biotechnology, Dalian University of Technology, Dalian 116024, China.
authors: Jingyun
authors: J
authors: Wang
authors: Department of Occupational and Environmental Health, Dalian Medical University, Dalian 116044, China.
authors: Yachen
authors: Y
authors: Li
authors: School of Life Science and Biotechnology, Dalian University of Technology, Dalian 116024, China. Electronic address: biosci@dlut.edu.cn.
authors: Yongming
authors: Y
authors: Bao
mesh_terms: D004800:Enzymes, Immobilized / Q000737:chemistry / Q000378:metabolism; D004951:Esterification; D005632:Fructose / Q000031:analogs & derivatives / Q000378:metabolism*; D005656:Fungal Proteins / Q000737:chemistry / Q000378:metabolism*; D007700:Kinetics; D007848:Laurates / Q000378:metabolism*; D008049:Lipase / Q000737:chemistry / Q000378:metabolism*; D017433:Protein Structure, Secondary; D012997:Solvents; D017550:Spectroscopy, Fourier Transform Infrared
chemical_list: D004800:Enzymes, Immobilized; D005656:Fungal Proteins; D007848:Laurates; D012997:Solvents; D005632:Fructose; C093667:Novozyme 435; D008049:Lipase; C431349:lipase B, Candida antarctica
keywords: ATR-FTIR; Candida antarctica lipase B; Degree of esterification; Fructose laurate; Sugar ester of fatty acid