Conformation change of glucose oxidase at the water-air interface

pi-A curve, Brewster angle microscope (BAM), quartz crystal microbalance (QCM) as well as LB film and circular dichroism (CD) spectrum have been used to study the assembly and folding behavior of glucose oxidase (GOD) monolayers spreading on the surface of CdCl2 solution or water. It was found that either methanol or CdCl2 could make GOD more hydrophobic so that they could easily float to the surface to form a monolayer and make the conformation of GOD changed. The monolayers spreading on CdCl2 solution were more compact than those on the pure water subphase. It has been shown that the ratio of alpha-helix to beta-sheet of GOD molecules could be enhanced by using Langmuir and Langmuir-Blodgett techniques. The relative enzyme activity combined with QCM measurements of GOD LB film proved that the relative enzyme activity became higher as the content of alpha-helix in GOD increasing. (C) 1999 Elsevier Science B.V. All rights reserved.