title: Effects of ionic surfactants used in reversed micelles on cutinase activity and stability.
abstract: The effects of aqueous surfactant solutions on the kinetics and stability of cutinase from Fusarium solani pisi were studied. The surfactant sodium bis[2-ethylhexyl]ester sulfosuccinic acid (AOT) acts as a pseudo-competitive inhibitor within a limited concentration range relative to the hydrolysis of short-chain p-nitrophenyl esters. For higher concentrations a hyperbolic mixed inhibition takes place. A pseudo-activation of hydrolysis in presence of AOT and hexadecyltrimethyl-ammonium bromide (CTAB) was observed. CTAB has similar effects on kinetics of cutinase. Cutinase revealed to be stable in CTAB solutions, with activity retention as high as 80%. AOT has a deleterious effect on the enzyme in the time course, resulting in acute loss of activity possibly related with unfolding of the protein structure. A relation between deactivation rate constants and AOT/cutinase concentration ratios is suggested. The presence of the linear alcohol, 1-hexanol, was included in these solutions, in the attempt to interpret the deactivation of cutinase when encapsulated in reversed micelle systems in the absence of this co-surfactant.
authors.affiliation: Centro de Engenharia Biológica e Química, Instituto Superior Técnico, Lisbon, Portugal. p1073@alfa.ist.utl.pt
authors.forename: A M
authors.initials: AM
authors.lastname: Gonçalves
authors.forename: A P
authors.initials: AP
authors.lastname: Serro
authors.forename: M R
authors.initials: MR
authors.lastname: Aires-Barros
authors.forename: J M
authors.initials: JM
authors.lastname: Cabral
mesh_terms: D002265:Carboxylic Ester Hydrolases / Q000378:metabolism*; D004795:Enzyme Stability; D007477:Ions; D007700:Kinetics; D008823:Micelles; D011994:Recombinant Proteins / Q000378:metabolism; D013500:Surface Tension; D013501:Surface-Active Agents / Q000737:chemistry*
chemical_list: D007477:Ions; D008823:Micelles; D011994:Recombinant Proteins; D013501:Surface-Active Agents; D002265:Carboxylic Ester Hydrolases; C019952:cutinase