My understanding of this is not perfect, but wouldn't answering the "actually does" question require a full biomolecular model of the cell, or even the whole organism? If so I see what you mean. I suppose that it might be possible to get around this by improving the theory of catalysts so that you could look at a site and say, "oh, this will act in such a way..." Dynamic quantum simulation of a few atoms at the active site is hardly easy but a far sight easier than the other.