Re: Hydrogen Cyanide and the Origin

[EMAIL PROTECTED] wrote in message news:<[EMAIL PROTECTED]>...
> Hydrogen Cyanide seem to be a key ingredient in origin scenarios
[snip]
> Also note that" HCN is more volatile than water, a concentration
> mechanism based on the evaporation to near dryness of a lake
> that contains small amounts of HCN wold not give concentrated
> cyanide solutions."

The usual concentration mechanism proposed for cyanide is freezing
rather than evaporation.  Freeze the H2O and the HCN is left in solution.
If, for some reason, you want both hot and cold, imagine a volcano poking
its way thru the Greenland icepack. 

But, I believe that a better way to provide cyanide to early life is 
as a ligand to transition metal ions.  CN- is much more stable as a ligand
than in solution - and it is more tightly bound than competing ligands
such as OH- and NH2-.  Thus, most of the pre-biosphere's HCN will be ligated
rather than dissolved.  The same applies to CO.  The metals were mostly
Fe++, with Ni++, Co++, Cu++, and Mo++ also around to provide some variety.

If you believe that geochemically (or astro-chemically) formed HCN
polymers took part in some kind of order-out-of-chaos heterotrophic origin
of life, then we are in disagreement.  More likely, IMHO, is that HCN was
first essential as a feedstock for lipid production.  That was the origin
of life, as I define life.  Much later, HCN and CO may have been feedstocks
for sugar and then nucleotide production, leading to an RNA world, but life
was probably already ancient by that time.  Life did not begin with the 
ribosome, and it didn't begin with an RNA replicase either.  Both were, no
doubt, important steps in the pre-common-ancestor evolution of life, but both
are far too complex to have arisen pre-biotically.

A pre-RNA biochemistry was probably based on interactions among lipid head
groups and complex ions.  Perhaps mineral surfaces were also involved.  You
should read Wachtershauser (sp?)  Much of his stuff is probably wrong, but
it is a better approach than basing theories of life's origin on a "soup"
idea that was generated back when people thought that there was something
magical about colloids.  Throw out the old soup.  Throw out the newer idea
that genetics can only come from informational polymers.  Throw out the
prejudice that interesting stuff only takes place INSIDE the bag of enzymes.
Notice that it is the bag itself that reproduces.  Ask how a bag can make
more bag material.  Notice that interesting things need to happen on both
the inside and the outside leaflets of the bag.  Also notice that the 
proton-motive force (PMF) is probably the ancestral energy pool and reaction
coupling mechanism.  Phosphate esters, diesters, and anhydrides came later.
The PMF may even antedate DeDuve's beloved thioesters. (IMHO)

Westheimer wrote a beautiful paper back in the 70s entitled "Why Nature Chose
Phosphates".  To my mind, the more interesting question is "When Did Nature
Choose Phosphates?".  Or, perhaps more interesting, "Where Did Nature Find
Phosphates?"  My guess is that She found them in deposits of calcium
metaphosphate minerals (deposited, of course by one of your drying cycles).
But, notice that in my theory, organisms already exist to use the energy
stored by the drying.  Your theory(s) seem to suggest that the organisms were
in some sense created (or at least refined) by the drying. Personally, I 
doubt it.