APPLICATION OF FLUORESCENCE SPECTROSCOPY TO THE STUDY OF PROTEINS AT INTERFACES

A new technique for studying the nature of adsorbed protein molecules based on fluorescence spectroscopy is described. The method was used for following the adsorption of bovine serum albumin (BSA) onto particulates. On random copolypeptide substrates of the type (Glu(OBzl)xAlay), (Glu(OBzl)xLeuy), or (Lys(CBZ)xLeuy), considerable fluorescence quenching was observed. The origin of this effect appears to be a combination of the energy exchange between the excited tryptophan residue of BSA and the excited triplet state (3Ba2b) or of 1Lb singlet state of the substrate, and quenching by adjacent molecules. Since energy exchange of this type can occur over a distance of 100 Å or so, it is possible to probe the protein environment of particles in the interfacial layer. It is concluded that even at low surface coverage, protein molecules are present adjacent to the surface in a nonadsorbed methoric" layer. © 1979."