Raman Senses Sugars On Proteins

Chemists in England have demonstrated for the first time that Raman spectroscopy can differentiate between the native and glycosylated forms of a protein (Anal. Chem., DOI: 10.1021/ac2012009). When pharmaceutical companies produce protein-based drugs, such as therapeutic antibodies, they must ensure the proteins have the proper sugar groups attached. The wrong sugars may decrease a protein’s effectiveness or even cause a harmful immune reaction, says Royston Goodacre of the University of Manchester, who led the research team. Scientists typically characterize glycoproteins by using mass spectrometry, which is time-consuming and destroys the sample, he notes. Because chemists have previously used Raman spectroscopy to pinpoint structural features in proteins, such as β-strands, Goodacre and colleagues decided to see whether Raman could monitor protein glycosylation. The Manchester scientists showed that they can distinguish between the spectra of RNase A and RNase B, the sugar-free and glycosylated forms, respectively, of bovine pancreatic ribonuclease, a well-characterized protein. By analyzing mixtures of RNase A and B at different relative concentrations, they were also able to quantify the fraction of protein that is glycosylated. Goodacre suggests drug companies could use the technique to analyze proteins nondestructively during production without hurting their yields.