Well, my last post on biological systems and their ingredients really touched a nerve (see here for an example). I guess I should, um, clarify my position before the leaky bottles of beta-mecaptoethanol start arriving by FedEx.
I already knew the reasons for several of the components I spoke about - EDTA, for example. And I realize that there's a reason for everything that's in there. But what throws me as a chemist is that some of these recipes seem to be handed on "just because they work" Does a particular enzyme prep need EDTA in it or not? Many times, no one checks, because it probably won't harm things and it's better to be on the safe side, so in it goes. It may be hard for a biologist to understand how odd that feels to a synthetic organic chemist, but I can tell you for sure that it does.
One of the commentors to the last post brought up an important point: biologists optimize for the function of a system. And that often means having a lot of buffers, chelators, cofactors, adjuvants, reducing agents, and chaperones floating around in there with your protein of interest, to keep it thinking that it's still in some kind of cellular environment, thus putting it in the mood to do what it's supposed to be doing. There's no point in trying to see how minimal you can make the system if it's working the way you want it to already.
But we chemists are minimalists. We optimize for the function of a system, too, but in our case, purity is usually a good first variable to tune up. The cleaner everything is in our reactions, the better it generally works. That means pure, distilled solvents, with no water in them. It means an inert gas atmosphere, so there's no reactive oxygen around. And it means that your starting materials and reagents should be as clean as you can practically get them, because when there's two percent of this or five percent of that in the flask, things often start to go wrong in unpredictable ways. When a reaction wipes out on us, the first thing we check is whether everything was clean enough.
So you can imagine how biology looks to an organic chemist, whose ideal reaction is a clear solution in a clear glass flask, with one pure solvent and two pure reactants cleanly converting to only one product. Biological systems, to us, look like trying to do science by adding squirts of barbecue sauce to bowls of beef stew. Of course, as the biologists know, the stuff in those bowls was derived from stew (and worse), and was born to the stuff. It won't work unless things achieve a certain level of stewiness, and the surest way to kill it would be to turn an organic chemist loose on it to clean it all up.