On Sun, 31 May 2009, Rhong Dhong wrote: > I have had the pop-science idea that the reason the proteins, and other > bits and pieces, found their mates, and found them so quickly, was that > at their scales, just randomly moving around meant that they were > destined to come near one another in a very short period of time.
I think that's the assumption made by the biochem community: it has to be explained by pure diffusion (random wandering and re-tries.) When I started questioning this, someone pointed out an old paper that actually tried some statistical calcs for one particular setup, and found that diffusion was orders of magnitude too slow to explain the reaction rates. Let me see if I can find the ref. Ah, it;s at the bottom of http://amasci.com/tesla/biores.html, below the links Here's one I remember. When a ribosome is spewing out a protein, it has to wait for the previous tRNA to move away, then it has to wait for one special tRNA with matched anticodon out of a large number of unmatched ones, to randomly drift in and dock at the ribosome. It's like shaking up a bag of keys, with one padlock, and waiting long enough for the right key to randomly get positioned near the keyhole. Then the lock changes code, and has to repeat the whole process. The sequence has to occur fast enough to explain the rate of protein synthesis by ribosomes. http://www.youtube.com/watch?v=B6O6uRb1D38 But that was old ideas, and today we know that water in cells is a near solid, "organized water," so diffusion of large molecules is greatly slowed. So the rate of protein synthesis is even more inexplicable than before. If the ribosome can issue a radio call for the next matched tRNA, ignore the unmatched ones, and have the matched one be ferried into place by "electrically biased diffusion," much is explained. As you say, diffusion would succeed over short scales, if there was some other force operating over long length scales. > > If they had some help from electrical forces which tended to pull them > together when they were in the vicinity of each other, then the two > factors guaranteed that adenine would quickly unite with thymine, > guanine with cytosine, etc., etc. > > So, even if they were relatively far apart to start with, should this > make much difference in their being able to get together? > (((((((((((((((((( ( ( ( ( (O) ) ) ) ) ))))))))))))))))))) William J. Beaty SCIENCE HOBBYIST website billb at amasci com http://amasci.com EE/programmer/sci-exhibits amateur science, hobby projects, sci fair Seattle, WA 206-762-3818 unusual phenomena, tesla coils, weird sci
