Saturday, September 29, 2012

Evolution (Not) Crucial in Antibiotics Breakthrough: How Science is Actually Done

Where is the best place to find low-cost, easy-to-produce, natural, robust and non toxic antibiotics? Easy, in our own bodies. Nature so often provides the solutions we are looking for and, as an aside, that is why the preservation of species from extinction is so important. In this case the solution is natural antibiotics which University of California at Berkeley researchers have confirmed to exist in the tails of certain proteins called cytokeratins. These proteins help our eyes, for example, ward off infections. The eye’s cornea is remarkably free of pathogens and the research reveals something about how these wonderful proteins work. Once again, however, the research was not motivated by evolutionary theory.

Proteins consist of a long chain of amino acids, attached one after the other. This chain, or backbone, is usually tightly coiled into a helix shape or stretched out into a strand shape. Occasionally the backbone folds back on itself and so adopts a turn shape. Proteins that are inserted into the cell membrane are usually helices for the helix shape can have a more oily surface to match the oily interior of the membrane.

The Berkeley researchers found that the cytokeratin tails apparently insert into the membrane of pathogen cells. The cytokeratin tails they investigated were 13 to 26 amino acids long and are rich in the simplest amino acid, glycine. Here, from the paper, are the sequences and their properties:

Glycine’s side chain is nothing but a mere hydrogen atom and as such it is the most flexible amino acid. So not surprisingly the cytokeratin tails do not adopt a fixed helix or strand shape, but rather a looser, less common, coil shape. It appears that the insertion of the tail into the pathogen’s membrane not only serves to immobilize the foreign cell, it also creates a pore in the membrane. Such pores are harmful to cells because they serve to neutralize the all-important chemical and electrical properties of the cell.

This new research is important for what it tells us about antibiotics and for what it tells us about science. Rationalists maintain that scientists must operate from a theory of origins in order to do science and that, in particular, that theory must be evolution. But science itself demonstrates that there is no such requirement.

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