Re: Hydrogen Cyanide and the Origin

<< 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. 

TH
I tend to think that when life began it was hot and hotter.
Freezing would answer the HCN question but not much else. We are stuck with the
liquid water range mostly. I tend to think to have drying and to have the
hydrogen bonded variants that seem so important - that the steam end is more
likely than the ice end. (I have suggested that before RNA world came a h-bond
world where variants of h-bonding were selected)

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. 

TH
There seems to me to be problems with having each of the following develop
separately; then somehow magically come together - aa, nucleic acids, lipid
production, etc.
I think more likely it was some symbiosis of all these under similar
circumstances. Thus in a wet/dry hot/cold cycle we could have symbiotic
molecules according to
temp, wet/dry, pH conditions. And every part of the day would favor certain
symbiants at that temp.
I think lipids was a part of that. But the bigger issue is this.  "Feed and
breed" (or whatever your def. of life is) is an adaptive respone to what?



 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.

TH
I agree. I think first there was the production of assorted monomers, then came
the h-bond world.  H-bonds could easily have many variants. Covalent bonds with
their high activation energy would hardly be selected for if it takes endless
energy to jump that fence.

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. 

TH
The bag and nucleic acids. I think both are a response to heat. (and most
likely other environment cycles of wet/dry and perhaps pH)  . If the bag alone,
then why would nucleic acids divide at all.

 Ask how a bag can make
more bag material. 

TH
Ask why that would better allow it to survive in its immediate environment.
What force is it trying to survive. And how does this ploy help it survive that
force.



 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?". 

TH
Let's go one step further. If life was such an advantage
why didn't salt, gold, or water 'feed and breed'?
I'm not being facetious. We are taking so much for granted in first life
scenarios that upon closer investigation, make no sense whatsoever.
Life had specific chemical properties that best adapted to specific variants in
a specific environment.
We need to know all of those specifics to even begin to approach a good
scenario.




 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.

 >>
TH
This is a fascinating topic that I think is ripe for
a big discovery.
Tom Hendricks