A somewhat lengthy but interesting article contrasting the relative simplicity of aircraft design to modelling biological processes. A sobering reminder of just how complex the human body is, how much we don’t know, and why progress in drug and other treatments remains painfully slow in many cases. Quote:
At first sight there indeed don’t seem to be too many differences between the two processes. Proteins and drugs (which are usually called “small molecules” in the trade) are machines with many moving parts, just like airplanes. They are buffeted by surrounding water molecules in the body just like airplanes are buffeted by airflow. And just like airplanes, their parts are dependent on each other’s motions. Of course, airplane design seems to depend on classical mechanics while drug design would probably need quantum mechanics, but that seems to mainly translate to a question of computational expense. If we can really conceptualize the concerted motion and concomitant functions of tens of thousands of gauges, valves, nuts and bolts, measuring instruments, flaps, wheels and innumerable pieces of metal and plastic in a Boeing 777, what stops us from similarly conceptualizing the interaction of myriad amino acids, water molecules and one small molecule in a test tube?
The answer to this question is something we are still working out, but the short answer is “biological complexity“. Accurate drug design from scratch will only be possible when we can realistically simulate and understand the structure and function of both small molecules and proteins in the body. A few months ago there was an article in a drug design journal by Walter Woltosz from a company called Simulations Plus which tries to model the metabolism of drugs. Woltosz wondered why we are not as good at designing drugs as we are at designing airplanes, and I blogged about his article here. My guess is that while computational drug design is certainly going to get better, I am not holding my breath before it has the predictive power of airplane design. What exactly makes the difference?