AVS 51st International Symposium
    Biomaterial Interfaces Monday Sessions
       Session BI-MoM

Paper BI-MoM7
Measurement of Conformational Changes of Surface Bound Biomolecules: a Novel Strategy for Analytical Biosensing

Monday, November 15, 2004, 10:20 am, Room 210D

Session: In-Situ Spectroscopy of Biomolecules at Interface
Presenter: D.A. Russell, University of East Anglia, UK
Authors: D.A. Russell, University of East Anglia, UK
L.M. May, University of East Anglia, UK
Correspondent: Click to Email
A large number of biomolecules change conformation upon interaction with specific substrates. Whilst spectroscopic techniques (such as CD, NMR and IR) provide sensitive measurement of secondary structure in solution, they are not amenable for the development of surface bound sensing technologies based on analyte induced conformational changes. Surface plasmon resonance (SPR) is a surface sensitive technique capable of measuring changes in refractive index (RI) that occur in proximity to the sensor interface. By depositing biomolecules onto the gold-coated sensor surface of an SPR instrument it is possible to measure changes of secondary structural conformation as a function of substrate concentration. A number of biomolecules including, polypeptides, proteins and enzymes, have been formulated as SAMs on SPR sensor surfaces and varying concentrations of substrates or mild denaturants have been passed over the monolayer surface to elicit secondary structural changes. For example, a dramatic increase in the SPR signal (m°) was observed when polylysine was induced into the alpha-helical conformation with ethanol. Similarly, the SPR signal was related to other secondary structures (including beta-sheet and random configurations) of both polypeptides and the protein Concanavalin A. The intensity of the SPR signal being related to the RI of the secondary structural configuration of the biomolecule. Development of this sensing strategy has focused on the self-assembly of urease in order to measure the conformational change of this enzyme as a function of heavy metals. On the sensor surface, the SPR signal from the urease monolayer linearly increased in intensity as a function of cadmium concentration in the range 0 - 10 mg/L. These data show that conformational changes of surface bound biomolecules can be measured and used analytically.