Surface-Enhanced Raman Spectroscopic Investigation of Human Immunoglobulin G Adsorbed on a Silver Electrode.

摘要

SERS spectra of human IgG adsorbed on a silver electrode from solution concentrations of 1.0 micromole IgG in pH 7.2 phosphate buffer are presented and spectral assignments made. Laser power of 50 mW was sufficient to obtain high-quality spectra. Overall enhancement was in the range of 104-105. The spectrum consisted only of vibrations from amino acid residues with functional groups that would complex with silver, including tyrosine, tryptophan, cystine, and acidic groups. No amide backbone stretches were observed. From the relative intensities of the vibrations, average conformations of the adsorbed amino acid groups were proposed. The selective enhancement, afforded to adsorbed residues, allowed monitoring of protein conformational changes at low coverage in high buffer ionic strength. (jes)