Enzymatic reactions with Raman

Thus this technique is especially suited to studying enzymatic reactions with considerable advantage. Until now the procedure for determining the active centrum of an enzyme was rather complex because enzymatic reactions are performed only in aqueous solutions and at very low concentrations. Thus, IR-spectroscopy and normal Raman techniques failed. Also, experiments to study enzymatic reactions in the crystalline phase will not succeed, for the native conformation of the enzymes in solution is a prerequisite for optimal reactivity. The usual technique, therefore, is a stepwise modification of the functional groups of either the enzyme or its substratum and the measurement of their kinetic behaviour. This very laborious procedure then provides some information concerning the active centrum. 

As discussed further in the following sections, there are other variations of rapid mixing/quench methods in which the enzymatic reaction is terminated by freezing the reaction mixture with liquid isopropane. The frozen sample is then analyzed hy electron paramagnetic resonance (EPR), solid-state NMR, or other spectroscopic techniques such as resonance Raman spectroscopy that can accommodate a solid sample. Perhaps the major limitation for implementation of this methodology is the sensitivity of the spectroscopic method and the requirement for large amounts of enzyme. ... 

Bredirick et al adsorbed CCD on a citrate-reduced silver colloid, and found that adsorbed CCD retains 60-85% of its enzymatic activity in the reaction of catechol substrate with O2 to give cisxis-muconate [112]. The first surface-enhanced resonance Raman spectroscopy (SERRS) study has demonstrated that the native conformation of CCD is retained in the adsorbed state. 

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