MANDELATE RACEMASE ASSAYED BY POLARIMETRY

An accurate and convenient assay for mandelate racemase based on polar imetry was developed by making use of the time-dependent decrease of t he optical rotation of the substrate (D- or L-mandelate) at 589 nm (Na -D-line) during the enzyme-catalyzed racemization. In comparison to th e indirect assay methods hitherto used, this method has the following advantages: (i) it is faster and more accurate than the two-enzyme red ox assay (which needs a membrane-bound protein fraction), (ii) it is a lso applicable to non-natural substrates other than mandelate, provide d their specific optical rotation is large enough and (iii) it does no t rely on expensive equipment such as circular dicroism.