The definition blurb says this site is for biochemists, but as there isn't a very clearly defined line (at least as far as I know) on the continuum from genetics to molecular biology, biochemistry, and organic chemistry, what will be criteria to figure out what goes where?
Be greedy and take everything that's even remotely biological? What about drugs?
A certain degree of overlap especially with Biochem is unavoidable and acceptable I think. Things like enzyme kinetics and structure would be better suited to Chemistry whereas mechanisms of enzyme action and things of that sort seem closer to to Biology.
My rule of thumb would be if there's gels of any sort involved, stick it in Biology.
There will most probably questions on Biology that would fit better in Chemistry, and vice versa. I do not see that as a bad thing, for mainly two reasons:
It is easy to migrate questions from one SE site to another, and following a migrated question to the next site may actually promote a higher exchange of users among the sites.
Those questions will be most probably borderline on-topic in either site. If they remain on the original site, it will expand the area of focus and will introduce novel topics to the users, thus expanding the knowledge beyond the area of comfort.
As a cell biologist, I had the opportunity to interact in more than one project with chemists. I can say that the result was quite interesting, for both parties.