Structure and reactivity of type-I copper sites

Summary Biological electron transfer is not well understood. The question is addressed in this contribution with reference to the so-called blue copper proteins, each of which has a single copper atom at its active centre. The redox activity (as probed by the electron self exchange reaction) of the Cu centre seems not to be affected. The electron self exchange reaction is known to proceed through His-117, and the hydrophobic patch is most important in the formation of the azurin/azurin encounter complex. Ph effects have not been observed on the three-dimensional structure ofA. denitrificans azurin, which may indicate that if present at all these have no direct physiological implications. Mutants are in process of construction.