Abstract
Time-resolved step-scan FTIR spectroscopy has been employed to probe the dynamics of the ba&sub3; oxidoreductase from Thermus thermophilus in the ns-μs time range and in the pH/pD 6-9 range. The data revealed a pH/pD sensitivity of the D372 residue and of the ring-A propionate of heme a&sub3;. Based on the observed transient changes a model in which the protonic connectivity of w941-w946-927 to the D372 and the ring-A propionate of heme a&sub3; is described.