title: Regio-selective lipase catalyzed hydrolysis of oxanorbornane-based sugar-like amphiphiles at air-water interface: A polarized FT-IRRAS study.
abstract: Interfacial hydrolysis of oxanorbornane-based amphiphile (Triol C16) by Candida rugosa lipase was investigated using real-time polarized Fourier transform-infrared reflection absorption spectroscopy (FT-IRRAS). The kinetics of hydrolysis was studied by analyzing the ester carbonyl ν(CO) stretching vibration band across the two dimensional (2D) array of molecules at the confined interface. In particular, we demonstrate Triol C16 to form Michaelis-Menten type complex, like that of lipid-substrate analogues, where the Triol C16 head group remained accessible to the catalytic triad of the lipase. The enzyme-induced selective cleavage of the ester bond was spectroscopically monitored by the disappearance of the intense ν(CO) resonance at 1736cm-1. Consequently, the in situ spectroscopic measurements evidenced selective ester hydrolysis of Triol C16 yielding Tetrol C2OH and Palmitic acid, which remained predominantly in the undissociated form at the interface. The conformation sensitive amide I (majorly ν(CO)) and the interfacial water reorganization suggested 2D ordering of the enzyme molecules following which interfacial reactions were employed towards probing the enzyme kinetics at the air/water interface. The investigation demonstrated further the potential of IRRAS spectroscopy for real-time monitoring the hydrolytic product formation and selectivity at biomimetic interfaces.
authors.affiliation: Department of Chemistry, Indian Institute of Technology Madras, Chennai 600036, India.
authors.forename: Nirod Kumar
authors.initials: NK
authors.lastname: Sarangi
authors.affiliation: Department of Chemistry, Indian Institute of Technology Madras, Chennai 600036, India.
authors.forename: M
authors.initials: M
authors.lastname: Ganesan
authors.affiliation: Department of Chemistry, Indian Institute of Technology Madras, Chennai 600036, India.
authors.forename: K M
authors.initials: KM
authors.lastname: Muraleedharan
authors.affiliation: Department of Chemistry, Indian Institute of Technology Madras, Chennai 600036, India. Electronic address: archita59@yahoo.com.
authors.forename: Archita
authors.initials: A
authors.lastname: Patnaik
mesh_terms: D000388:Air; D055162:Biocatalysis; D019086:Bridged Bicyclo Compounds, Heterocyclic / Q000737:chemistry / Q000378:metabolism*; D002175:Candida / Q000201:enzymology; D006868:Hydrolysis; D008049:Lipase / Q000737:chemistry / Q000378:metabolism*; D015394:Molecular Structure; D009636:Norbornanes / Q000737:chemistry / Q000378:metabolism*; D017550:Spectroscopy, Fourier Transform Infrared; D013237:Stereoisomerism; D013501:Surface-Active Agents / Q000737:chemistry / Q000378:metabolism*; D014867:Water / Q000737:chemistry / Q000378:metabolism
chemical_list: D019086:Bridged Bicyclo Compounds, Heterocyclic; D009636:Norbornanes; D013501:Surface-Active Agents; D014867:Water; D008049:Lipase
keywords: Enzymatic hydrolysis; FT-IRRAS; Glycolipid; Interfacial kinetics; Langmuir monolayer