Abstract
Abstract Objectives α-amylases hydrolyze α-1,4 glycosidic bonds in starch. ILs used as co-solvent in different enzymatic reactions to improve activity, selectivity and stability of enzymes. In this study, fluorescence spectroscopy method was used to explain the effect of [emim][lactate] on kinetic and thermal stability of Aspergillus oryzae α-amylase. Methods Effect of different concentrations of [emim][lactate] on activity of α-amylases was determined. Kinetic parameters, optimum pH and temperature and thermal stability were determined and compared with absence of [emim][lactate]. Intrinsic fluorescence spectroscopy for Trp residues was performed for both presence and absence of [emim][lactate]. Results Activity of α-amylase decreases in presence of [emim][Lac]. Moreover, Km of α-amylase in the presence of [emim][lactate] increases while Vm decreased. Optimum temperature in presence of [emim][lactate] increases from 45 to 50 °C while optimum pH decreases from 9 to 7. Thermal stability of α-amylase in the presence of [emim][lactate] is similar to that in the absence of [emim][lactate] at 40 and 50 °C but decreases at 60 °C. Intrinsic fluorescence spectroscopy shows unfolding of native structure of α-amylase is dependent on [emim][lactate] concentration. Conclusions Presence of [emim][lactate] ionic liquid as co-solvent leads to structural unfolding of α-amylase and loss of its activity and thermal stability.
Highlights
Objectives: α-amylases hydrolyze α-1,4 glycosidic bonds in starch
Presence of [emim][lactate] ionic liquid as co-solvent leads to structural unfolding of α-amylase and loss of its activity and thermal stability
Imidazolium based ionic liquids (ILs) may increase the solubility of starch and activity of α-amylase should be increased
Summary
Objectives: α-amylases hydrolyze α-1,4 glycosidic bonds in starch. ILs used as co-solvent in different enzymatic reactions to improve activity, selectivity and stability of enzymes. Conclusions: Presence of [emim][lactate] ionic liquid as co-solvent leads to structural unfolding of α-amylase and loss of its activity and thermal stability. Physical characteristics (such as melting point, viscosity, density, solubility, and hydrophobicity) and thermal properties of ILs depends on the species of cation and anion as well as the length of Akhavan et al.: α-amylase in the presence of [emim][lactate] ionic liquid the alkyl groups on the cation [8, 9]. The use of ILs as a part of reaction media in enzyme-catalyzed reactions has attracted interest in recent years This is the first report that evaluates the activity, stability, kinetic, and structural changes in α-amylase from Aspergillus oryzae in the presence of 1-ethyl3-methylimidazolium L-(+)-lactate IL. It is important to know that if ILs physical properties alone lead to alterations in enzyme kinetic and stability or structural changes due to interaction with ILs are effective
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
