Modulation of cellulase activity by charged lipid bilayers with different acyl chain properties for efficient hydrolysis of ionic liquid-pretreated cellulose.
The stability of cellulase activity in the presence of ionic liquids (ILs) is critical for the enzymatic hydrolysis of insoluble cellulose pretreated with ILs. In this work, cellulase was incorporated in the liposomes composed of negatively charged 1-palmitoyl-2-oleoyl-sn-glycero-3-phosphoglycerol (POPG) and zwitterionic phosphatidylcholines (PCs) with different length and degree of unsaturation of the acyl chains. The liposomal cellulase-catalyzed reaction was performed at 45°C in the acetate buffer solution (pH 4.8) with 2.0g/L CC31 as cellulosic substrate. The crystallinity of CC31 was reduced by treating with 1-butyl-3-methylimidazolium chloride ([Bmim]Cl) at 120°C for 30min. The liposomal cellulase continuously catalyzed hydrolysis of the pretreated CC31 for 48h producing glucose in the presence of 15wt% [Bmim]Cl. The charged lipid membranes were interactive with [Bmim](+), as elucidated by the [Bmim]Cl-induced alterations in fluorescence polarization of the membrane-embedded 1,6-diphenyl-1,3,5-hexatriene (DPH) molecules. The charged membranes offered the microenvironment where inhibitory effects of [Bmim]Cl on the cellulase activity was relieved. The maximum glucose productivity GP of 10.8 mmol-glucose/(hmol-lipid) was obtained at the reaction time of 48h with the cellulase incorporated in the liposomes ([lipid]=5.0mM) composed of 50mol% POPG and 1,2-dilauroyl-sn-glycero-3-phosohocholine (DLPC) with relatively short and saturated acyl chains.
Department of Applied Molecular Bioscience, Yamaguchi University, 2-16-1 Tokiwadai, Ube, 755-8611, Japan.
Kai
K
Mihono
Department of Applied Molecular Bioscience, Yamaguchi University, 2-16-1 Tokiwadai, Ube, 755-8611, Japan.
Takeshi
T
Ohtsu
Department of Applied Molecular Bioscience, Yamaguchi University, 2-16-1 Tokiwadai, Ube, 755-8611, Japan.
Mai
M
Ohtani
Department of Applied Molecular Bioscience, Yamaguchi University, 2-16-1 Tokiwadai, Ube, 755-8611, Japan. Electronic address: yosimoto@yamaguchi-u.ac.jp.
Makoto
M
Yoshimoto
Department of Applied Molecular Bioscience, Yamaguchi University, 2-16-1 Tokiwadai, Ube, 755-8611, Japan.
Akio
A
Kamimura
D002384:Catalysis; D002480:Cellulase / Q000737:chemistry / Q000378:metabolism*; D002482:Cellulose / Q000737:chemistry*; D006868:Hydrolysis; D007093:Imidazoles / Q000737:chemistry; D052578:Ionic Liquids / Q000737:chemistry*; D008051:Lipid Bilayers / Q000737:chemistry*; D008081:Liposomes / Q000737:chemistry; D010713:Phosphatidylcholines / Q000737:chemistry; D010715:Phosphatidylglycerols; D014242:Trichoderma / Q000201:enzymology*
D007093:Imidazoles; D052578:Ionic Liquids; D008051:Lipid Bilayers; D008081:Liposomes; D010713:Phosphatidylcholines; D010715:Phosphatidylglycerols; C502841:1-butyl-3-methylimidazolium chloride; C060037:1-palmitoyl-2-oleoylglycero-3-phosphoglycerol; D002482:Cellulose; D002480:Cellulase
Cellulase; Charged liposomes; Glucose production; Insoluble cellulose; Ionic liquid