title: Optimization of oligomeric enzyme activity in ionic liquids using Rhodotorula glutinis yeast phenylalanine ammonia lyase.
abstract: Phenylalanine ammonia lyase (E.C.4.3.1.24, PAL) activity of Rhodotorula glutinis yeast has been demonstrated in four commonly used ionic liquids. PAL forward reaction was carried out in 1-butyl-3-methylimidazolium methyl sulfate ([BMIM][MeSO4]), 1-butyl-3-methylimidazolium tetrafluoroborate ([BMIM][BF4]), 1-butyl-3-methylimidazolium hexafluorophosphate ([BMIM][PF6]) and 1-butyl-3-methylimidazolium lactate ([BMIM][lactate]). Our experiments have revealed that PAL is catalytically active in ionic liquids and the enzyme activity in ([BMIM][PF6]) is comparable to that obtained in aqueous buffer medium. Different conditions were optimized for maximal PAL forward activity including time of incubation (30.0min)L-phenylalanine substrate concentration (30.0mM), nature of buffer (50.0mM Tris-HCl), pH (9.0), temperature (37°C), and speed of agitation (100 rev min-1). Under these optimized conditions, about 83% conversion of substrate to product was obtained for the PAL forward reaction that was determined using UV spectroscopy at 290nm. PAL reverse reaction in ([BMIM][PF6]) was determined spectrophotometrically at 520nm; and about 59% substrate conversion was obtained. This data provides further knowledge in enzyme biocatalysis in non-aqueous media, and may be of importance when studying the function of other oligomeric/multimeric proteins and enzymes in ionic liquids.
authors.affiliation: Dalhousie University, Halifax, NS, B3H 4J2, Canada.
authors.forename: Christiaan C
authors.initials: CC
authors.lastname: Barron
authors.affiliation: Department of Chemistry, Cape Breton University, 1250 Grand Lake Road, Sydney, Nova Scotia, B1P 6L2, Canada.
authors.forename: Brandon J D
authors.initials: BJ
authors.lastname: Sponagle
authors.affiliation: Department of Environmental Engineering, Daegu University, Gyeongbuk, 712-714, South Korea.
authors.forename: Pugazhendhi
authors.initials: P
authors.lastname: Arivalagan
authors.affiliation: Department of Chemistry, Cape Breton University, 1250 Grand Lake Road, Sydney, Nova Scotia, B1P 6L2, Canada. Electronic address: godwin_dcunha@cbu.ca.
authors.forename: Godwin B
authors.initials: GB
authors.lastname: D'Cunha
mesh_terms: D055162:Biocatalysis; D002021:Buffers; D005656:Fungal Proteins / Q000737:chemistry / Q000378:metabolism*; D006863:Hydrogen-Ion Concentration; D007093:Imidazoles / Q000737:chemistry; D052578:Ionic Liquids / Q000737:chemistry; D007700:Kinetics; D010650:Phenylalanine Ammonia-Lyase / Q000737:chemistry / Q000378:metabolism*; D020836:Protein Structure, Quaternary; D012248:Rhodotorula / Q000201:enzymology*; D012997:Solvents / Q000737:chemistry
chemical_list: D002021:Buffers; D005656:Fungal Proteins; D007093:Imidazoles; D052578:Ionic Liquids; D012997:Solvents; D010650:Phenylalanine Ammonia-Lyase
keywords: Biocatalysis; Ionic liquids; Oligomeric enzyme activity; Phenylalanine ammonia lyase; Rhodotorula glutinis