title: Surfactant tail length-dependent lipase activity profile in cationic water-in-oil microemulsions.
abstract: The catalytic activity of Chromobacterium viscosum lipase (CV-lipase) was estimated across varying surfactant tail lengths (C-10-C-18) in water-in-oil (w/o) microemulsions of cationic surfactants containing four different hydroxyethyl-substituted head groups. An attempt to find a correlation, if any, between the activity of interfacially solubilized lipase and the varying surfactant tails was made for the first time in micellar enzymology. The second-order rate constant, k2, in lipase-catalyzed hydrolysis of p-nitrophenyl-n-hexanoate at pH 6.0 and 25 degrees C shows an improvement in enzyme activity (approximately 30-140%) across different head groups of amphiphiles with increasing tail lengths in varying solution compositions. Improvement of enzyme activity is prominent in ascending from C-10 to C-14/C-16, depending on the nature of polar head group. The hydrolytic activity of lipase in different surfactant (50 mM)/water/isooctane/n-hexanol with varying z= [alcohol]/[surfactant] (6.4 or 4.8) was amplified by 25-250% with increment in surfactant tail length in comparison with widely used cationic w/o microemulsions having solution compositions (z=16). As a notable outcome of this research, we found w/o microemulsions of 25 mM tetradecyltrimethylammonium bromide/water/isooctane/n-hexanol (z=8) producing the highest ever activity of lipase in any w/o microemulsions.
authors.affiliation: Department of Biological Chemistry, Indian Association for the Cultivation of Science, Jadavpur, Kolkata 700032, India.
authors.forename: Antara
authors.initials: A
authors.lastname: Dasgupta
authors.forename: Debapratim
authors.initials: D
authors.lastname: Das
authors.forename: Rajendra Narayan
authors.initials: RN
authors.lastname: Mitra
authors.forename: Prasanta Kumar
authors.initials: PK
authors.lastname: Das
mesh_terms: D002384:Catalysis; D002412:Cations / Q000737:chemistry; D002861:Chromobacterium / Q000201:enzymology; D004655:Emulsions; D004789:Enzyme Activation; D006868:Hydrolysis; D008049:Lipase / Q000737:chemistry*; D008823:Micelles; D015394:Molecular Structure; D009821:Oils / Q000737:chemistry*; D013499:Surface Properties; D013501:Surface-Active Agents / Q000138:chemical synthesis / Q000737:chemistry*; D014867:Water / Q000737:chemistry
chemical_list: D002412:Cations; D004655:Emulsions; D008823:Micelles; D009821:Oils; D013501:Surface-Active Agents; D014867:Water; D008049:Lipase; C454481:lipase, Chromobacterium viscosum