This proposal will provide funds for an integrated rapid mixing system that will allow stopped flow, continuous flow, freeze quench and chemical quench experiments to be carried out. In the stopped or continuous flow modes reactions can be studied by absorption, fluorescence or Raman scattering and circular dichroism. In the chemical and freeze quench modes reactive intermediates can be trapped and then characterized by electron paramagnetic resonance, nuclear magnetic resonance, or other spectroscopies. Projects will be conducted by six major users from the Departments of Biochemistry and Physiology and Biophysics. The instrumentation will also be available to several additional users and will be part of a NIH supported Training Program in Molecular Biophysics. In general, the instrumentation will be applied to the study of protein and ribozyme folding, several enzyme substrate interactions, ligand binding in hemoglobins, protein-DNA interactions and protein translocation.