Wow, check out this post by Paul Nelson over at Evolution News.
Now, the paper I retrieved for my co-worker, entitled “The Levinthal paradox of the interactome,” Protein Science 20 (2011):2074-79, explains why the space of “being alive” is so much vastly smaller, and harder to find, than the space of being “not alive.” The paper is short (only six pages) and was written by two structural biologists, Peter Tompa of Vrije Universiteit in Brussels and George Rose of Johns Hopkins University, neither of whom is an intelligent-design advocate. But the paper’s arguments bear so strongly on the design debate, and represent so remarkable a challenge to widely held assumptions about (for instance) the origin of cells, that its effect promises to be far-reaching. As in, revolutionary.
[...]Tompa and Rose draw a number of lessons from their calculations. They argue, first, that any increase in biological realism will only make the Levinthal interactome paradox worse:
Of course, there are additional complicating factors such as alternative splicing, post-translational modifications, non-pairwise macromolecular interactions, incorrect complex formation that is adventitiously stable, and so forth. However, even neglecting such complications, the numbers preclude formation of a functional interactome by trial and error complex formation within any meaningful span of time. This numerical exercise…is tantamount to a proof that the cell does not organize by random collisions of its interacting constituents.But secondly, what they call “the most profound conclusion” from their analysis bears directly on widely held assumptions about the origin of life.
A highly enriched soup of proteins and nucleic acids will never form a functional cell, even if lipid bilayer membranes were provided to help these materials become organized. Indeed, the fully functional contents of a living cell, once the wall or membrane enclosing them has been breached (thus, killing the cell), move irreversibly in the direction of non-living chemistry. Humpty Dumpty, once he cracks, does not reconstitute, but enters what Tompa and Rose call the “zone of chaos,” never to return.
Tompa and Rose have sketched the theoretical basis for why this happens:
[O]ur calculations of combinatorial complexity [show] that the emergent interactome could not have self-organized spontaneously from its isolated protein components. Rather, it attains its functional state by templating the interactome of a mother cell and maintains that state by a continuous expenditure of energy. In the absence of a prior framework of existing interactions, it is far more likely that combined cellular constituents would end up in a non-functional, aggregated state, one incompatible with life…The spontaneous origination of a de novo cell has yet to be observed; all extant cells are generated by the division of pre-existing cells that provide the necessary template for perpetuation of the interactome.
Tompa and Rose spell out other implications of their analysis (e.g., for medicine and synthetic biology), but maybe we’ve piqued your curiosity enough already. This paper deserves your attention. As noted, for a close circle of us at Discovery and Biologic, it’s the most interesting and significant paper we’ve read in years.
Dr. Nelson’s post explains a bit more with pictures.