Origin of life: the polymerization problem
by Jonathan Sarfati
A well-publicised paper by Claudia Huber and Günter Wächtershäuser
in Science proposed a scenario for a materialistic origin of life from
non-living matter.1 They correctly
state:
The activation of amino acids and the formation of peptides under primordial conditions
is one of the great riddles of the origin of life.
Indeed it is. The reaction to form a peptide bond between two amino acids to form
a dipeptide is:
Amino acid 1 + amino acid 2 → dipeptide + water
H2NCHRCOOH +H2NCHR′COOH → H2NCHRCONHCHR′COOH
+ H2O (1)
The free energy change(ΔG1) is about 20–33 kJ/mol, depending
on the amino acids. The equilibrium constant for any reaction (K) is the equilibrium
ratio of the concentration of products to reactants. The relationship between these
quantities at any Kelvin temperature (T) is given by the standard equation:
K = exp (–ΔG/RT)
where R is the universal gas constant (= Avogadro’s number x Boltzmann’s
constant k) = 8.314 J/K.mol
For reaction (1),
K1 = [H2NCHRCONHCHR′COOH][H2O]/[H2NCHRCOOH][H2NCHR′COOH]
= 0.007 at 298 K
where a compound in square brackets symbolises the concentration of that compound.
This means that if we start with a concentrated solution of 1 M (mol/l) of each
amino acid, the equilibrium dipeptide concentration would be only 0.007 M. Since
tripeptides have two peptide bonds, the equilibrium tripeptide concentration would
be 0.0072 M or 5x10–5 M. For a non-specific polypeptide
with 100 peptide bonds (101 amino acids), the equilibrium concentration would be
3.2 x 10–216 M. NB: the problem for evolutionists is even worse,
because life requires not just any polymers, but highly specified ones.
Since the equilibrium concentration of polymers is so low, their thermodynamic tendency
is to break down in water, not to be built up. The long ages postulated
by evolutionists simply make the problem worse, because there is more time for water’s
destructive effects to occur. High temperatures, as many researchers advocate, would
accelerate the breakdown. The famous pioneer of evolutionary origin-of-life experiments,
Stanley Miller, points out that polymers are ‘too unstable to exist in a hot
prebiotic environment’.2,3 A recent article in New Scientist
also described the instability of polymers in water as a ‘headache’
for researchers working on evolutionary ideas on the origin of life.4 It also showed its materialistic bias by saying
this was not ‘good news’. But the real bad news is the
faith in evolution which overrides objective science.
Some evolutionary scenarios
The analysis above doesn’t mean it’s impossible to make polypeptides.
Consider the expression for the equilibrium constant K: if [H2O] is lowered,
then [polypeptide] must increase. One approach is to drive off the water with heat,
as proposed by Sydney Fox.5 However,
his experiments required a large excess of the trifunctional amino acids (i.e. they
can combine with three other molecules), but these are produced very sparingly in
typical simulation experiments.6 The
heat also destroys some vital amino acids and results in highly randomized polymers.
Another problem is that all the chiral amino acids are racemized, that is, a 50/50
mixture of left and right handed molecules is produced, which is unsuitable for
life.7The large excess of trifunctional
amino acids results in extensive branching, unlike biological polymers. The required
heating and cooling conditions are geologically unrealistic—there is no known
place on earth where amino acids could be dumped and polypeptides would result.
Finally, Fox’s experiments required very concentrated and pure amino acids,
while any hypothetical primordial soup would be impure and grossly contaminated
with other organic chemicals that would destroy them.8
Another way to remove water is with certain high-energy chemicals that absorb water,
called condensing agents. If the reaction between condensing agent C and
water is:
C + H2O → D (2)
and if ΔG2 of reaction (2) is negative and large enough, it can
couple with reaction (1):
H2NCHRCOOH + H2NCHR′COOH + C → H2NCHRCONHCHR′COOH
+ D (3)
ΔG3 = ΔG1 + ΔG2. If ΔG3
is large and negative, the equilibrium constant for reaction 3, K3, will
be large, and this could conceivably produce reasonable quantities of polymers.
Some researchers used the condensing agent dicyanamide (N=CNHC=N) to produce some
peptides from glycine, even claiming, ‘dicyanamide mediated polypeptide synthesis
may have been a key process by which polypeptides were produced in the primitive
hydrosphere.’9
However, the biggest problem is that condensing agents would readily react with
any water available. Therefore it is a chemical impossibility for the primordial
soup to accumulate large quantities of condensing agents, especially if there were
millions of years for water to react with them. Yet the above experiment used a
30-fold excess of dicyanamide. And even with these unrealistic conditions, 95% of
the glycine remained unreacted, and the highest polymer formed was a tetrapeptide.10
Organic chemists can certainly make polypeptides, using intelligent planning of
a complex multi-stage synthesis, designed to prevent wrong reactions occurring.11 Living cells also use an elegant
process to make polypeptides. This involves the use of enzymes to activate amino
acids (and nucleotides) by combining them with the high-energy compound ATP (adenosine
triphosphate), to overcome the energy barrier.
Such high-energy compounds are not formed in prebiotic simulation experiments, and
are very unstable.
Chain termination
To form a chain, it is necessary to react bifunctional monomers, that is,
molecules with two functional groups so they combine with two others. If a unifunctional
monomer (with only one functional group) reacts with the end of the chain, the chain
can grow no further at this end.12
If only a small fraction of unifunctional molecules were present, long polymers
could not form. But all ‘prebiotic simulation’ experiments produce
at least three times more unifunctional molecules than bifunctional
molecules.13 Formic acid (HCOOH)
is by far the commonest organic product of Miller-type simulations. Indeed, if it
weren’t for evolutionary bias, the abstracts of the experimental reports would
probably state nothing more than: ‘An inefficient method for production
of formic acid is here described …’ Formic acid has little
biological significance except that it is a major component of ant (Latin formica)
stings.
A realistic prebiotic polymerisation simulation experiment should begin with the
organic compounds produced by Miller-type experiments, but the reported ones always
exclude unifunctional contaminants.
Wächtershäuser’s theory
Günter Wächtershäuser is a German patent attorney with a doctorate
in organic chemistry. He is highly critical of the usual primordial soup ideas of
the origin of life. As the quote at the beginning of this article shows, he recognises
that polymerization is a big problem. However, not willing to abandon his evolutionary
faith, he proposes that life began as a cyclic chemical reaction on the surface
of pyrite (FeS2). The energy to drive this cycle is said to come from
the continued production of pyrite from iron and sulfur. However, he admits that
this proposal is for the most part, ‘pure speculation’.14 Fellow origin-of-life researcher Gerald Joyce
claims that the acceptance of Wächtershäuser’s theory owes more to
his legal skills than to its merit.14 Stanley Miller calls it ‘paper chemistry’.15
In their latest well-publicised experiment, Huber and Wächtershäuser activated
amino acids with carbon monoxide (CO) and reacted them in an aqueous slurry of co-precipitated
(Ni,Fe)S using either hydrogen sulfide (H2S) or methanethiol (CH3SH)
at 100° C at a pH of 7–10.
We should also note that Huber and Wächtershäuser started off with very
favourable conditions for chemical evolution. Although ‘the researchers have
not yet shown that this recipe can produce amino acids’,16
they used a strong solution (0.05 M) of left-handed amino acids (or the achiral
glycine), with no other organic material. Of course, any ‘primordial soup’
would have been dilute, impure and racemic. It would have contained many unifunctional
molecules and other organic compounds that would have destroyed amino acids. Stanley
Miller also points out that Huber and Wächtershäuser used concentrations
of CO far higher than are realistic in nature.16
Even under their favourable conditions (due to intelligent design!), all they produced
was a small percentage of dipeptides (0.4–12.4%) and an even tinier amount
of tripeptides (0.003%)—calculated from reported quantities. Huber and Wächtershäuser
also reported that ‘under these same conditions dipeptides hydrolysed rapidly’!
The exclusive ‘left-handedness’ required for life7
was destroyed in the process. They excuse this by pointing out that some cell wall
peptides have right-handed amino acids. But this misses the point—enzymes
that break down cell walls are designed for exclusively left-handed amino acids,
so an occasional right-handed amino acid is the perfect defence in a left-handed
world.
A final irony is that one of their previous experiments converted CO into acetic
acid (CH3COOH) under similar conditions with CH3SH and a (Ni,Fe)S
slurry.17 Since acetic acid is unifunctional,
this would prevent long polymers from forming under the conditions
Huber and Wächtershäuser propose!
Did scientists create life, or did the media create hype?
Newspapers around the world reported this experiment. Some went as far as claiming:
‘German chemists have produced living cells from a combination of amino acids
…’18
If true, then this would be remarkable. Even the simplest decoded free-living organism,
Mycoplasma genitalium, has 482 genes coding for all the necessary proteins,
including enzymes. These proteins are composed of about 400 amino acids each on
average, in precise sequences, and all in the ‘left-handed’ form.19 Of course, these genes are only functional with
pre-existing translational and replicating machinery, a cell membrane, etc. But
Mycoplasma can only survive by parasitizing more complex organisms, which
provide many of the nutrients it cannot manufacture for itself. So evolutionists
must postulate an even more complex first living organism with even more genes.
However, as shown above, all Huber and Wächtershäuser produced were a few
dipeptides and even fewer tripeptides. While they didn’t make the deceitful
claim quoted above, their evolutionary faith means that they see far more significance
in their experiment than it deserves.
The next day, the same newspaper wrote ‘WA Museum evolutionary biologist Ken
McNamara said if life could be created artificially, it could emerge naturally given
the right conditions.’20 How
absurd—does this mean that because we can create cars artificially (with loads
of intelligent input), it proves they could emerge naturally (without intelligence!)?
People should not be surprised by such biased reporting. We should compare the hype
about ‘Martian life’ with the near silence about the fact that this
claim has been thoroughly discredited, even according to most secular scientists.21,22,23,24
The cynical media disdain for truth was well illustrated at a symposium sponsored
by the Smithsonian Institution. Ben Bradlee, editor of The Washington Post,
said:
‘To hell with the news! I’m no longer interested in news. I’m
interested in causes. We don’t print the truth. We don’t pretend to
print the truth. We print what people tell us. It’s up to the public to decide
what’s true.’25
A detailed survey of the political and social beliefs of producers, editors, writers,
and staff in the television industry26
shows that they are biased against Christian morality. Two-thirds of them believe
the structure of American society is faulty and must be changed. 97% say women should
have the right to decide whether they want to have an abortion, 80% believe there’s
nothing wrong with homosexual relations, and 51% see nothing wrong with adultery.
And they openly admit that they push their ideas into the programs they create for
their audiences. The media’s willingness to push evolutionary hype is consistent
with their anti-Christian stance.
Conclusion
Despite over-optimistic science reports and very biased and hyped-up media reports,
scientists have not even come close to ‘creating life in the test-tube’.
Even if they do manage this feat, it will be the result of intelligent design. Ordinary
undirected chemistry moves in the wrong direction—for example, as shown in
this article, biological polymers tend to break apart, not form.
References
- Huber, C. and Wächtershäuser, G., 1998. Peptides by activation
of amino acids with CO on (Ni,Fe)S surfaces: implications for the origin of life.
Science 281(5377):670–672. Return to text.
- Miller, S.L. and Lazcano, A., 1995. The origin of life—did
it occur at high temperatures? J. Mol. Evol. 41:689–692.
Return to text.
- Miller has also pointed out that the RNA bases are destroyed very
quickly in water at 100°C—adenine and guanine have half lives of about
a year, uracil about 12 years, and cytosine only 19 days. Levy, M and Miller, S.L.,
1998. The stability of the RNA bases: Implications for the origin of life. Proc.
Natl. Acad. Sci. USA 95(14):7933–38. Return
to text.
- Matthews, R., 1997. Wacky Water. New Scientist
154(2087):40–43. Return to text.
- Fox, S.W. and Dose, K., 1977. Molecular Evolution and the Origin
of Life, Marcel Dekker, New York. Return to text.
- Glycine, the simplest amino acid, is by far the commonest amino
acid formed. See Ref. 13 for some typical yields. Return to text.
- For more information on chirality and life, see
Sarfati, J.D., 1998. Origin of Life: The chirality
problem . Journal of Creation 12(3):263–266.
Return to text.
- Such criticisms and more are found in Thaxton, C. B., Bradley,
W. L. & Olsen, R. L., 1984. The
Mystery of Life’s Origin, Philosophical Library Inc., New York.
See
online version (off site). Return to text.
- Steinman, G., Kenyon, D.H. and Calvin, M., 1966. Biochim. Biophys.
Acta 124:339. D.H. Kenyon, also co-author of the evolutionary
book Biochemical Predestination, has since become a creationist.
Return to text.
- Gish, D.T., 1972. Speculations
and Experiments Related to Theories of the Origin of Life: A Critique, ICR
Technical Monograph No. 1, Institute for Creation Research, San Diego, CA.
Return to text.
- Streitwieser, A. and Heathcock, C.H., 1981. Introduction to
Organic Chemistry, 2nd Ed., Macmillan, NY, ch. 29. Return
to text.
- Volmert, B., 1985. Das Molekül und das Leben, Rowohlt,
pp. 40–45. Cited in: Wilder-Smith, A.E., 1987. The Scientific Alternative
to Neo-Darwinian Theory: Information Sources and Structures, TWFT Publishers,
Costa Mesa, CA, p. 61. Return to text.
- Dickerson, R.E., 1978. Chemical Evolution and the Origin of Life.
Scientific American 239(3):62–102. A chart
on p. 67 shows a typical yield from one of Miller’s experiments. 59,000 mmol
carbon in the form of methane yielded as the main unifunctional products: 2,330
mmol formic acid, 310 mmol lactic acid 150, mmol acetic acid and 130 mmol propionic
acid. Four amino acids found in modern proteins were produced: 630 mmol glycine,
340 mmol alanine, 6 mmol glutamic acid, and 4 mmol aspartic acid. Return
to text.
- Horgan, J., 1991. In the beginning. Scientific American
264(2):100–109. Quote on p. 106. Return to text.
- Horgan, ref. 14, p. 102. Return to text.
- Vogel, G., 1998. ‘A sulfurous start for protein synthesis?’
Science 281(5377): 627–629 (Perspective on Ref.
1). Return to text.
- Huber, C. and Wächtershäuser, G., 1998. Activated acetic
acid by carbon fixation on (Fe,Ni)S under primordial conditions. Science
276(5310):245–247. Return to text.
- The West Australian, 11 August 1998.
Return to text.
- Fraser, C.M., et al. 1995. The minimal gene complement
of Mycoplasma genitalium. Science 270(5235):397–403;
Perspective by A. Goffeau. Life with 482 Genes, same issue, pp. 445–6.
Return to text.
- The West Australian, 12 August 1998. Return
to text.
- Scott, E.R.D., Yamaguchi, A. and Krot, A.N., 1997. Petrological
evidence for shock melting of carbonates in the martian meteorite ALH84001. Nature
387:377–379. Return to text.
- Bradley, J.P., Harvey, R.P. and McSween, H.Y., 1997. No ‘nanofossils’
in martian meteorite. Nature 390(6659):454–456.
Return to text.
- Holmes, R., 1996. Death knell for Martian life. New Scientist
152 (2061/2):4. Return to text.
- Kerr, R.A., 1998. Requiem for life on Mars? Support for microbe
fades. Science, 282(5393):1398–1400.
Return to text.
- Bradlee, B., 1989. Reported by Brooks, D., 1989. The Wall
Street Journal, 10 October. Return to text.
- Lichter, S.R., Lichter, L.S. and Rothman, S., 1992.
Watching America: What Television Tells Us About Our Lives. Return to text.
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