Chirality of life: Another false positive?

By PvM

Creationists have considered the ‘mystery’ of the chirality of life a problem inaccessible to scientific explanation. Of course, science as usual takes little notice of claims to ignorance and has provided yet another explanation for the chirality of life.

Point in case, a recent paper in Nature shows that:

Chirality, the molecular version of right- and left-handedness, has intrigued chemists ever since Pasteur found mirror-image tartaric acid crystals. The synthesis of molecules in a single chiral form is usually achieved by using a chiral entity from the outset. But in some reactions the formation of a chiral product seems to be further amplified. Most current explanations implicate autocatalysis as the source of this asymmetry. An alternative mechanism is demonstrated this week. This new approach generates a strong bias towards one chiral form from a small initial imbalance, based on the equilibrium solid–liquid phase behaviour of amino acids. As this takes place in aqueous solution, the process might explain how a prebiotic world, with left- and right-handed molecules present in equal numbers, could turn into a living world where biomolecules favour one chiral form.

Editor’s Summary ‘Chemistry mirrors life’

The paper in question is:

Martin Klussmann, Hiroshi Iwamura, Suju P. Mathew, David H. Wells, Jr Urvish Pandya, Alan Armstrong and Donna G. Blackmond Thermodynamic control of asymmetric amplification in amino acid catalysis Nature 441, 621-623 (1 June 2006)

Based on the work by Dembski, this ‘researcher’ concludes that

So we are left to conclude that homochirality came about by some directed, non-stochastic mechanism

So let’s look at the ‘design inference’ in more detail

Let’s first establish that the chirality of life matches the definition of complex specified information.

Complexity

However, this does not solve the mystery of where the optical activity in living organisms came from in the first place. A recent world conference on ‘The Origin of Homochirality and Life’ made it clear that the origin of this handedness is a complete mystery to evolutionists.4 The probability of forming one homochiral polymer of N monomers by chance = 2–N. For a small protein of 100 amino acids, this probability = 2–100 = 10–30. Note, this is the probability of any homochiral polypeptide. The probability of forming a functional homochiral polymer is much lower, since a precise amino acid sequence is required in many places. Of course, many homochiral polymers are required for life, so the probabilities must be compounded. Chance is thus not an option.

All that is needed is a polymer of length 500 (500 bits) to meet Dembski’s stringent limit but Dembski also seemed satisfied with 40 out of 41 in the Caputo case. In other words, the complexity criterion in met. But what about specification?

Specification The specification is simple. In biology a function is all that is needed for specification to exist and thus any functional polymer will do. But in addition, another specification is a “Sorted set of amino-acids where all amino acids posess a left chirality”.

Based on the observation that chirality of life is complex and specified I conclude, and various other creationists and ID activists agree, that there exists a design inference that chirality of life required a designer.

So if in fact the research turns out to be relevant, and chirality of life has been resolved, will ID accept that it has been falsified?

Or will it argue that

  1. The original claim by the explanatory filter was flawed
  2. ID is still a logical possibility (for instance via front loading)
  3. Ignore the whole issue in the hope that it will go away
  4. The scenarios proposed are not specific enough and are ‘just so stories’ as opposed to the story about the unembodied designer.

And will someone explain to me how ID would explain chirality of life?

The authors conclude:

Here we have established that the coupling of solid–liquid phase behaviour and amino acid catalysis results in an efficient and robust mechanism for asymmetric amplification. This finding suggests that amino acids may have played a role in the evolution of biomolecular homochirality23. One can easily imagine the coexistence of solid and dissolved amino acids under a range of environmental conditions in a prebiotic landscape, and high ee could then evolve from an initially small imbalance in ee if (1) the amino acid forms a racemic compound rather than a conglomerate; (2) the amino acid exhibits high enantiopurity at its eutectic; and (3) the amino acid acts with high selectivity as an asymmetric catalyst in solution phase transformations. In fact, our studies show that serine meets the first two criteria, and recent work24 has demonstrated that serine catalyses certain asymmetric aldol reactions with high enantioselectivity; it has also been highlighted as one of a small number of amino acids likely to have played an important role in prebiotic chemistry25, 26. A scenario for homochiral evolution based on our amplification mechanism was hinted at some years ago27, and it also shares some similarities with the suggestion that chiral enrichment may result from the selective dissolution of only one (enantiopure) crystal of a conglomerate in a microenvironment28, but seems ultimately much simpler. A particularly appealing feature of the scenario we outline here is that it is based on an equilibrium mechanism, in contrast to the far-from-equilibrium environments invoked in kinetically induced amplification via autocatalytic reactions or crystallizations29, 30. Finally, we note that further enhancements in solution-phase enantiomeric excess may be discovered in more complex multi-component systems with a greater number of equilibrium solid and liquid phases. This possibility and the influence of interactions between different amino acids and between amino acids and other molecules such as sugars is the subject of ongoing investigations by our group, as is the search for high selectivity in amino-acid-catalysed reactions of potential biological relevance.

Relevant Links

Update:

Complex forms in proteins, enzymes, DNA, and other biological structures demonstrated by their constituent molecules in regard to size, shape, quantity, orientation, sequence, chirality, and integration imply intelligent design was necessary for the first life on earth. Intelligence is capable of designing complex form;

HOUSE BILL NO. 911, 92ND GENERAL ASSEMBLY, INTRODUCED BY REPRESENTATIVES COOPER (155) (Sponsor), REINHART, DAVIS (19), NIEVES, PHILLIPS, EMERY AND HUNTER (Co-sponsors). Pre-filed December 19, 2003, and copies ordered printed.

Also HOUSE BILL NO. 1722, 92ND GENERAL ASSEMBLY INTRODUCED BY REPRESENTATIVES COOPER (155) (Sponsor), DAVIS (19), NIEVES, EMERY AND STEVENSON (Co-sponsors). Read 1st time April 7, 2004, and copies ordered printed.