Tuesday, August 19, 2008

Knowledge and mystery

"Science takes the mystery out of life." How often have I heard that complaint from someone too stubborn to learn a bit of science. Nothing, it seems to me, could be further from the truth.

An article in a recent issue of Science recounts progress on the protein-folding problem. Proteins are long sequences of amino acids, which are themselves rather simple molecules, just twenty types of which account for the chemistry of life. DNA specifies the sequence -- three steps on the double helix code for each of the amino acids -- and through the intermediary of RNA assembles the protein chain. Then the chain -- which can be hundreds or thousands of amino acids long -- all on its own and with remarkable alacrity folds up into a characteristic shape, like a wad of string, but with nooks and crannies and protrusions that help determine the protein's function. You and I are pretty much a buzzing commerce of proteins, proteins canoodling and nooking each other, doing what proteins do.

So what is the "protein folding problem"? Start with a given sequence of amino acids and predict the three-dimensional shape of the protein. The shape will be the particular "wad of string" that has the lowest free energy level -- like a marble rolling to the bottom of a bowl, except on vastly more complex scale. Researchers have the rules of folding more or less in hand, but to do the necessary calculations requires colossal computing power -- sometimes hundreds of thousands of computers linked in tandem grinding away, trying different configurations, seeking the one with lowest free energy. The prize for success is understanding how nature does the folding in a flash, and perhaps drugs that will repair or enhance protein function.

Does this take the mystery out of life? Well, in one sense, yes. We will soon know how proteins fold. But, lordy, when you know what is going on in every cell of our bodies, second by second, the huge, elegant, utterly simple, amazingly complex spinning and weaving and checking and correcting and jiggling and winding and unwinding in trillion of cells, trillions of protein factories, humming and churning to some cosmic tempo -- if all of that doesn't stand out as a mystery more worthy of attention than the half-baked superstitions that attract so much human notice, then...

...then one must be comatose or incorrigibly incurious.

(The schematic image of a globin protein is from www.answers.com.)