Purification and characterization of an alcohol dehydrogenase with an unusual specificity towards glycerol from Thermus thermophilus

The purification and characterization of an NAD+-dependent and zinc containing alcohol dehydrogenase (ADH) from Thermus thermophilus (TTHADH) is described. The enzyme could be purified with 25-fold purification and 68% yield using a single chromatographic step. The enzyme was found to be a tetramer (170 kDa) of identical subunits. The pH optimum of the purified enzyme was 8.8 and the temperature optimum was found to be 80 °C. Thermal denaturation curves were determined by monitoring the CD values at 222 nm and the Tm was found to be 89 °C. The enzyme showed much higher activity towards glycerol as compared to short chain primary and secondary alcohols. This thermostable enzyme was also highly stereospecific in oxidation of glycerol and converted glycerol into d-glyceraldehyde. The enzyme which converts glycerol into a chiral molecule like d-glyceraldehyde opens up several synthetic opportunities.