title: Action of Humicola lanuginosa lipase on mixed monomolecular films of tricaprylin and polyethylene glycol stearate.
abstract: The hydrolysis catalyzed by Humicola lanuginosa lipase (HLL) of pure tricaprylin (TC) or stearate of polyethylene glycol 1500 (PEG-St) as well as their mixtures spread as monomolecular films were studied. The catalytic transformation of the two substrates TC or PEG-St into their respective reaction products was detected by measuring simultaneously the decrease in the film area and the surface potential using the "zero order" trough at constant surface pressure. A kinetic model describing the enzymatic hydrolysis was developed. The surface concentrations of the two substrates and their respective reaction products as well as the values of the global kinetic constants of hydrolysis were determined. The experimentally obtained global kinetic constants of the catalytic action of HLL against TC and PEG-St present in mixed monolayers of TC/PEG-St are approximately the same as in the case of pure monolayers. These obtained results give some indications that the activity of enzyme is not significantly affected by the different molecular environments in the mixed monolayers.
authors.affiliation: Biophysical Chemistry Laboratory, Department of Physical Chemistry, University of Sofia, J. Bourchier Street 1, 1126 Sofia, Bulgaria. tzivanova@chem.uni-sofia.bg <tzivanova@chem.uni-sofia.bg>
authors.forename: Tz
authors.initials: T
authors.lastname: Ivanova
authors.forename: K
authors.initials: K
authors.lastname: Mircheva
authors.forename: G
authors.initials: G
authors.lastname: Dobreva
authors.forename: I
authors.initials: I
authors.lastname: Panaiotov
authors.forename: J E
authors.initials: JE
authors.lastname: Proust
authors.forename: R
authors.initials: R
authors.lastname: Verger
mesh_terms: D001203:Ascomycota / Q000201:enzymology*; D002210:Caprylates / Q000737:chemistry*; D002384:Catalysis; D006863:Hydrogen-Ion Concentration; D006868:Hydrolysis; D007700:Kinetics; D008049:Lipase / Q000737:chemistry*; D008956:Models, Chemical; D011092:Polyethylene Glycols / Q000737:chemistry*; D013499:Surface Properties; D014280:Triglycerides / Q000737:chemistry*
chemical_list: D002210:Caprylates; D014280:Triglycerides; D011092:Polyethylene Glycols; C003637:tricaprylin; C009314:polyethylene glycol monostearate; D008049:Lipase