title: Toluene promotes lid 2 interfacial activation of cold active solvent tolerant lipase from Pseudomonas fluorescens strain AMS8.
abstract: The utilization of cold active lipases in organic solvents proves an excellent approach for chiral synthesis and modification of fats and oil due to the inherent flexibility of lipases under low water conditions. In order to verify whether this lipase can function as a valuable synthetic catalyst, the mechanism concerning activation of the lid and interacting solvent residues in the presence of organic solvent must be well understood. A new alkaline cold-adapted lipase, AMS8, from Pseudomonas fluorescens was studied for its structural adaptation and flexibility prior to its exposure to non-polar, polar aprotic and protic solvents. Solvents such as ethanol, toluene, DMSO and 2-propanol showed to have good interactions with active sites. Asparagine (Asn) and tyrosine (Tyr) were key residues attracted to solvents because they could form hydrogen bonds. Unlike in other solvents, Phe-18, Tyr-236 and Tyr-318 were predicted to have aromatic-aromatic side-chain interactions with toluene. Non-polar solvent also was found to possess highest energy binding compared to polar solvents. Due to this circumstance, the interaction of toluene and AMS8 lipase was primarily based on hydrophobicity and molecular recognition. The molecular dynamic simulation showed that lid 2 (residues 148-167) was very flexible in toluene and Ca(2+). As a result, lid 2 moves away from the catalytic areas, leaving an opening for better substrate accessibility which promotes protein activation. Only a single lid (lid 2) showed the movement following interactions with toluene, although AMS8 lipase displayed double lids. The secondary conformation of AMS8 lipase that was affected by toluene observed a reduction of helical strands and increased coil structure. Overall, this work shows that cold active lipase, AMS8 exhibits distinguish interfacial activation and stability in the presence of polar and non-polar solvents.
authors.affiliation: Enzyme and Microbial Technology Research Centre, Universiti Putra Malaysia, 43400 Serdang, Malaysia; Department of Biochemistry, Faculty of Biotechnology and Biomolecular Sciences, Universiti Putra Malaysia, 43400 Serdang, Malaysia.
authors.forename: Norhayati
authors.initials: N
authors.lastname: Yaacob
authors.affiliation: Enzyme and Microbial Technology Research Centre, Universiti Putra Malaysia, 43400 Serdang, Malaysia; Department of Biochemistry, Faculty of Biotechnology and Biomolecular Sciences, Universiti Putra Malaysia, 43400 Serdang, Malaysia. Electronic address: mshukuri@upm.edu.my.
authors.forename: Mohd Shukuri
authors.initials: MS
authors.lastname: Mohamad Ali
authors.affiliation: Enzyme and Microbial Technology Research Centre, Universiti Putra Malaysia, 43400 Serdang, Malaysia; Department of Biochemistry, Faculty of Biotechnology and Biomolecular Sciences, Universiti Putra Malaysia, 43400 Serdang, Malaysia.
authors.forename: Abu Bakar
authors.initials: AB
authors.lastname: Salleh
authors.affiliation: Enzyme and Microbial Technology Research Centre, Universiti Putra Malaysia, 43400 Serdang, Malaysia; Department of Microbiology, Faculty of Biotechnology and Biomolecular Sciences, Universiti Putra Malaysia, 43400 Serdang, Malaysia.
authors.forename: Raja Noor Zaliha Raja Abdul
authors.initials: RNZRA
authors.lastname: Rahman
authors.affiliation: Enzyme and Microbial Technology Research Centre, Universiti Putra Malaysia, 43400 Serdang, Malaysia; Department of Cell Biology and Molecule, Faculty of Biotechnology and Biomolecular Sciences, Universiti Putra Malaysia, 43400 Serdang, Malaysia.
authors.forename: Adam Thean Chor
authors.initials: ATC
authors.lastname: Leow
mesh_terms: D055162:Biocatalysis; D002118:Calcium / Q000494:pharmacology; D020134:Catalytic Domain; D003080:Cold Temperature; D004789:Enzyme Activation; D004795:Enzyme Stability; D006860:Hydrogen Bonding; D057927:Hydrophobic and Hydrophilic Interactions; D007477:Ions; D008024:Ligands; D008049:Lipase / Q000737:chemistry / Q000378:metabolism*; D056004:Molecular Dynamics Simulation; D017433:Protein Structure, Secondary; D011551:Pseudomonas fluorescens / Q000201:enzymology*; D012997:Solvents / Q000494:pharmacology*; D014050:Toluene / Q000494:pharmacology*; D014867:Water / Q000737:chemistry
chemical_list: D007477:Ions; D008024:Ligands; D012997:Solvents; D014867:Water; D014050:Toluene; D008049:Lipase; D002118:Calcium
keywords: Cold-active lipase AMS8; Docking; Interfacial activation; Molecular dynamic; Organic solvents; Protein stability