Raman difference spectroscopy and the energetics of enzymatic catalysis

We have thus shown the use of OMA Raman spectrometers, with some special precautions, are capable of measuring difference spectra to fairly high subtraction accuracy. In our studies on the dehydrogenases, we have reported results on cofactors and substrates bound to these enzymes. We have obtained the Raman signals from groups like the nucleotide, adenine, phosphate moieties, single carbonyl moieties, and so forth when bound to ca. 40000 molecular weight proteins. It seems clear that this technique is capable of measuring not only bound molecules, but signals of specific protein residues. For example, a particular residue may be isotopically labelled or changed into another using the techniques of protein engineering. Subtracting the spectrum of the native protein from that of the modified protein would yield the spectrum of the chosen residue. Moreover, there seems no reason that small groups in other macromolecular systems, like nucleic acid assemblies, could not be studied using the same methodology.