Talk:High-energy phosphate

message: Thanks for the concise energetic picture. I had pictured ATP molecules flying around as charged molecular ions in molecular mass spectrographs and hadn't ever considered that the things might not be stable at all outside water. 
ATP is not even very stable IN water, except at extraordinary concentrations, and with some Mg2+ to cut the charge-charge interactions in the polyphosphate. 
This brings up the two worst problems in organic evolution (evolution of life to the one-cell stage). From one self-replicating prokaryote cell to us seems straightforward, but getting to one cell is not. The basic reason for this is that all the polymers of life, both proteins and nucleic acids, are not stable as polymers in water. They tend to break down into monomers. The idea that some "primordial soup" would make polymers like this from any reasonable concentration of monomers in a water-based primordial soup (some type of ocean or pool), just won't fly. It's just not going to happen no matter how long you have. So the Stanley Miller-Leslie Orgel experiments that make monomer-thingies from gases and energy are interesting, but they don't get past the next step, which is a worse one, of how to string these monomers up in to polymers of life. 
Life does it, of course, by coupling all the polymerizations in proteins, DNA and RNA to ATP-hydrolysis. And then it makes ATP by the damnest irreproducibly-complex Rube Goldberg contraption involving a membrane (the second big problem), AND a proton gradient across the membrane, AND an ATP synthase which is a complex 8 unit protein even in prokaryotes. And it needs this membrane to keep the H+ gradient up-- no primordial soup can work this. So where is the chicken and where is the egg? With no ATP you can't make a protein like an ATP synthase, and without some high-energy compound like ATP you can't make polymers of any kind, protein or RNA. So you need to START with ATP, or something like it, and a lot of it. The synthesis of it has to be coupled to some energy-producing reaction, or else it is an input from space.
It's a problem so bad that some Russian suggests that a giant meteorite made of polyphosphate slammed into a little pond somewhere and provided all the polyphosphate pro-anhydric-polymeric potential for the putting-together of all the polymers of the first protolife. Sounds wonky to me, but it's still the best idea I've heard so far on this. Everybody else ignores what it is a totally fundamental problem. Okay, how ELSE are you going to make nucleotides? Put in nucleotides and it all goes off into RNA-world with no problem. But you have to INPUT these.
Panspermia helps a little, since it gives us some more billions of years for all this to happen someplace else. But we still run up against thet time limit of the Big Bang and the need to make at least some second-generation stars. Okay 5 billion more years, but we need a mechnaism.
How about another type of life entirely, which we don't see? I've been wondering if we might not even need some kind of semi-creationist scenario ("semi," as this doesn't require a God-with-no-origin). Semi-creation would posit that irreducibly complex RNA-protein life was created by some other type of non-RNA, non-protein life that itself used some kind of polymer system that isn't so nutty and unstable in water as P~P~P, so that it DID make it from scratch, 10 billion years ago. Perhaps with 5 billion extra years, they then they had time enough to go from non-life to one-cell to intelligence, to hyper-intelligence (though not omniscience/omnipotence), and then they made the first simple RNA-protein-membrane-ATP-synthase life, using ATP as the basic entropy-energy currency, and sent it out as seeds, ala panspermia. Leaving us all here, 5 billion years after THAT, scratching our water-filled proteinacious heads with muscles that use ATP to power the action, and looking very confused. SBHarris 01:36, 9 December 2012 (UTC)
thread_title:  ATP in vacuum and the origin of life (organic evolution)