Monitoring structural changes of proteins on solid phase using surface plasmon resonance sensor

There are several techniques to detect the structural changes of proteins in solution. However it is difficult to apply them to the protein on solid phase. We show the possibility to monitor two kinds of signal changes for proteins immobilized on dextran resin by BIAcore biosensor based on surface plasmon resonance (SPR). Proteins with different properties were attached to sensor surfaces and various denatured states were induced by treatment with acidic or basic solutions. As a result, at least two different types of signal changes were detected real-time and these signal changes arose during and after the treatment with each solution that we denoted as in situ and post values, respectively. The in situ value seemed to have a strong correlation to the total charge state of the proteins which can be calculated theoretically, and the post value to the degree of structural changes of the proteins. This method is expected to be applied to various analyses and give us new information about the behavior of proteins on solid phase.