In point of fact, however, many new biotechniques are taking advantage of the lessons of evolution to answer the problems of protein therapeutic drug design (PTDD). Normally, PTDD involves using computers to display images of the protein's structure that are then manipulated rationally to create the necessary structural changes to obtain the desired results. Then site-directed mutagenesis is used to make these changes in the real protein. There are, however, a number of problems with this approach. There are many different traits (thermostability, activity, solubility, DNA binding, etc.) that work cooperatively to create the enzyme's catalytic capability, and often we don't know which should be changed to best improve catalysis. Nor can we predict what will happen to the other traits as a result. Often no structural data is available for a given protein. Even just doing the site-directed mutagenesis can be a royal pain.
However, all of this can be bypassed using evolution-derived techniques. These take advantage of the blind nature of the "evolutionary algorithm" of mutation and natural selection to obtain improved and/or novel catalytic functions. Four requirements have to be satisfied for success: the desired function must be physically possible; the function must be biologically or evolutionarily possible; it must be possible to make chimeric libraries complex enough to contain rare beneficial combinations; and there must be a way to rapidly screen or select for the desired function. The third requirement is routine work in any molecular biology lab throughout the world. Requirements one and two can be satisfied by the family shuffling concept or by taking advantage of proteins that already have a binding activity (like antibodies) to evolve catalytic activity as well (Fuji, I, _et al._ 1998. _Nature Biotechnology_ 16:463-472). Requirement four is the most tricky, but a new technique invol
ving water-in-oil emulsion to trap a transcription/translation reaction mixture in bacterium-size vesicles may be a step in the right direction (Tawfik, DS, AD Griffiths. 1998. "Man-made cell-like compartments for molecular evolution." _Nature Biotechnology_ 16:652-656).
After all this, it's difficult to see how anyone could still harbor any certainty for the claim that it is too improbable for novel proteins to evolve from random amino acid sequences. But this discussion also puts the lie to another creationist claim, that evolution has contributed nothing to modern society. Very shortly now it may in fact provide the very basis for creating new therapeutics to fight communicable, metabolic and genetic diseases. I thank God that in all His wisdom, He chose to create evolution.
Kevin L. O'Brien
"Good God, consider yourselves fortunate that you have John Adams to abuse, for no sane man would tolerate it!" William Daniels, _1776_