Time-dependent XAS studies of trapped enzyme-substrate complexes of alcohol dehydrogenase from Thermoanaerobacter brockii.

The understanding of structure-function relationships in proteins has been significantly advanced with the advent of the biotechnological revolution. A goal yet to be realized for many metalloenzyme systems is to characterize the dynamic changes in structure that bridge the static endpoints provided by crystallography. We present here a series of edge and EXAFS spectra of the metalloenzyme alcohol dehydrogenase from Thermoanaerobacter brockii (Tb ADH) complexed with its substrate. The enzyme-substrate complexes were trap ped by fast freezing at various times, following their enzyme activity. Our edge and EXAFS analyses both reveal the time-dependent changes in the stru cture of the active site of TbADH.