Do you have an example of some molecules that would be joined in an experiment?
Once you get DNA oligos in there you can do computation, as X binds X', and Y to Y'. So you can have all sorts of complex synthetic & designed interactions using chemistry that is both seamless and doesn't interfere with normal molecular biolgy.
Once you have proteins, you can localize particular chemistries.
I'd accept:
- elucidating a new signal transduction pathway
- discovering an uncharacterized enzyme
- measuring a biochemical constant of a known molecule (Kd e.g.)
- discovering a new drug target that then gets exploited