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Author Topic:   The Recurrent Problem of Chirality
Dr Adequate
Member (Idle past 402 days)
Posts: 16113
Joined: 07-20-2006

Message 21 of 81 (334186)
07-22-2006 12:32 AM
Reply to: Message 20 by RAZD
07-21-2006 9:45 PM

Chirality is autocatalytic.
A peptide replicator can amplify the proportion of a single chirality in an initially random mixture of left- and right-handed fragments:
Saghatelian, A., Y. Yokobayashi, K. Soltani and M. R. Ghadiri. 2001. A chiroselective peptide replicator; Nature 409: 797-801.
A demonstration of autocatalysis of chirality in amino acids:
Suju P. Mathew, Hiroshi Iwamura* and Donna G. Blackmond : Amplification of Enantiomeric Excess in a Proline-Mediated Reaction, Angewandte Chemie International Edition Vol 43, Issue 25 (June 21, 2004)
Self-assemblies on two-dimensional surfaces amplify a single handedness:
Zepik, H. et al. 2002. Chiral amplification of oligopeptides in two-dimensional crystalline self-assemblies on water; Science 295: 1266-1269
Serine forms stable clusters of a single handedness which can select other amino acids of like handedness; these clusters also incorporate other biologically important molecules such as glyceraldehyde, glucose, and phosphoric acid.
Takats, Zoltan, Sergio C. Nanita and R. Graham Cooks. 2003. Serine octamer reactions: indicators of prebiotic relevance; Angewandte Chemie International Edition 42: 3521-3523.
More of the same. You get the picture :
Sandra Pizzarello and Arthur L. Weber Prebiotic Amino Acids as Asymmetric Catalysts, Science 20 February 2004: Vol. 303. no. 5661, p. 1151
And yet another mechanism:
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)
The homeochirality of living species:
Pedro Cintas, Chirality of Living Systems: A Helping Hand from Crystals and Oligopeptides Angewandte Chemie International Edition, Volume 41, Issue 7 , Pages 1139 - 1145
Left handed amino acids catalyze production of dextrose sugars:
Pizzarello, Sandra, Arthur L. Weber. 2004 Prebiotic Amino Acids as Asymmetric Catalysts Science Vol 303, Issue 5661, 1151, 20 February 2004
The presence of borate minerals produces sugars in right-handed form:
Ricardo, A., Carrigan, M. A., Olcott, A. N., Benner, S. A.. 2004 Borate Minerals Stabilize Ribose Science January 9; 303: 196
Dextrose sugars fall out of the sky:
Sephton, Mark A. 2001 Meteoritics: Life’s sweet beginnings? Nature 414, 857 - 858 (20 Dec)
A mechanism by which a small initial imbalance in chirality can become overwhelming :
Kenso Soai, Takanori Shibata, Hiroshi Morioka & Kaori Choji. Asymmetric autocatalysis and amplification of enantiomeric excess of a chiral molecule, Nature 378, 767 - 768 (28 December 1995);
Shows a large and symmetric population of D and L crystals moving into complete chiral purity, with one of the enantiomers completely disappearing.
Cristobal Viedma, Chiral Symmetry Breaking During Crystallization: Complete Chiral Purity Induced by Nonlinear Autocatalysis and Recycling, Phys. Rev. Lett. 94, 065504 (2005)
Edited by Dr Adequate, : Trying to fix one of the links.

This message is a reply to:
 Message 20 by RAZD, posted 07-21-2006 9:45 PM RAZD has replied

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 Message 23 by RAZD, posted 07-22-2006 9:28 AM Dr Adequate has not replied

Dr Adequate
Member (Idle past 402 days)
Posts: 16113
Joined: 07-20-2006

Message 22 of 81 (334187)
07-22-2006 12:38 AM

Edited by Dr Adequate, : Double post

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