In order to study the effects of ionic surfactants on bacterial luciferase

the cationic surfactant dodecyltrimethylammonium biomide (DTAB) and anionic surfactant sodium dodecylsulfate (SDS) were chosen.For comparison with bacterial luciferase

α-amylase was used since these two enzymes have similar electrostatic potential and charged active sites.After the enzymes were treated with the surfactants

the catalytic properties of bacterial luciferase andα-amylase were assayed

and fluorescence spectroscopy and circular dichroism (CD) were used to analyze the alteration of the protein structure.The results showed that when the DTAB concentration was low

the cationic surfactant DTAB enhanced the enzymatic activities of bacterial luciferase andα-amylase.On the other hand

the anionic surfactant SDS did not alter the enzymatic activity.The main interaction of cationic surfactant DTAB and the negatively charged surface of the proteins was the ionic interaction

which could alter the environment for the enzyme to work when the DTAB/enzyme molar ratio was low.However

at high cationic surfactant concentration

the ionic interaction and hydrophobic interaction might destroy the secondary and tertiary structures of the proteins

leading to the loss of enzymatic activities.