ASU researcher may have discovered key to life before its origin on Earth

Molecular asymmetry is due to electron orbital configurations. Nothing new here.

It's well known, the righ-handed aminoacids or peptides are hydrolyzed faster due the chirality of water clusters and they can be more sensitive to polarized cosmic radiation, too.

http://www.newsci...895.html
http://www.rsc.or...ness.asp
http://www.rsc.or...rity.asp

Chirality In Life Still Awaits Elucidation

A. From "...key to life before its origin on Earth?"
http://www.physor...html#tab

When scientists synthesize these molecules in the laboratory, half of a sample turns out to be left-handed and the other half right-handed. But the amino acids that are the building blocks of terrestrial proteins are all left-handed, while the sugars of DNA and RNA are right-handed. The mystery as to why this is the case, parallels in many of its queries those that surround the origin of life...

Thanks to the pristine nature of this meteorite, we were able to demonstrate that other extraterrestrial amino acids carry the left-handed excesses in meteorites and, above all, that these excesses appear to signify that their precursor molecules, the aldehydes, also carried such excesses, Pizzarello said. other words, a molecular trait that defines life seems to have broader distribution as well as a long cosmic lineage.

B. From "Allosteric, chiral-selective drug binding to DNA"
http://www.pnas.o...2032.pdf

(Allosteric: of, relating to, undergoing, or being a change in the shape and activity of a protein, as an enzyme, that results from combination with another substance at a point other than the chemically active site)

DNA is polymorphic and exists in a variety of distinct conformations. Duplex DNA can adopt a variety of sequence-dependent secondary structures that range from the canonical right-handed B form through the left-handed Z conformation. Multistranded triplex and tetraplex structures are now known to exist. All of these unique conformations may play important functional roles in gene expression.

C. Chirality in life still awaits elucidation

First, reasearch findings should be stated scientifically correctly. In A above NOT "a molecular trait that defines life seems to have broader distribution as well as a long cosmic lineage%u201D, but YES "a molecular conformation dominant in Earth life may have broader distribution and additional cosmic presence.

Next, re in A above "the mystery as to why this is the case":

My conjecture about the probable reasons for the prevailing chirality:

Darwinian evolution started at life's day one, with the genesis of the first organisms, the replicating oligomers, pre-archaea genes. It started under yet-unknown energetic conditions, by a serendipitous accident, with oligomeric (RNA?) conformations, in a soup containing all their essential molecular progenitors. These Conformations happened to absorb the amounts of energy enabling their polymerization, to lengths precipitated as determined by the nature and conditions of the soup.

The sugars and the nitrogen-based compounds that, together with the phosphates, are the components of the genes-organisms, are chiral. There probably is an energetic advantage in homochirality and chiral homogeneity for the self-replication of biopolymers.

This serendipitous accident set up a matrix-field of energy with a potential extended between its source, the sun radiation and the precipitating organisms. This was the genesis of the ongoing formation and maintenance of Earth's biosphere.

And since the biosphere started it could only evolve in more favorable energetic directions and towards stabler components. Survival. After all this is evolution.

But this is a conjecture. Chirality in life still awaits elucidation...


Dov Henis

Chirality In Life Still Awaits Elucidation

A. From "...key to life before its origin on Earth?"
http://www.physor...html#tab

When scientists synthesize these molecules in the laboratory, half of a sample turns out to be %u201Cleft-handed%u201D and the other half %u201Cright-handed.%u201D But the amino acids that are the building blocks of terrestrial proteins are all %u201Cleft-handed,%u201D while the sugars of DNA and RNA are %u201Cright-handed.%u201D The mystery as to why this is the case, %u201Cparallels in many of its queries those that surround the origin of life...%u201D

Thanks to the pristine nature of this meteorite, we were able to demonstrate that other extraterrestrial amino acids carry the left-handed excesses in meteorites and, above all, that these excesses appear to signify that their precursor molecules, the aldehydes, also carried such excesses,%u201D Pizzarello said. %u201CIn other words, a molecular trait that defines life seems to have broader distribution as well as a long cosmic lineage.%u201D

B. From "Allosteric, chiral-selective drug binding to DNA"
http://www.pnas.o...2032.pdf

(Allosteric: of, relating to, undergoing, or being a change in the shape and activity of a protein, as an enzyme, that results from combination with another substance at a point other than the chemically active site)

DNA is polymorphic and exists in a variety of distinct conformations. Duplex DNA can adopt a variety of sequence-dependent secondary structures that range from the canonical right-handed B form through the left-handed Z conformation. Multistranded triplex and tetraplex structures are now known to exist. All of these unique conformations may play important functional roles in gene expression.

C. Chirality in life still awaits elucidation

First, reasearch findings should be stated scientifically correctly. In A above NOT "a molecular trait that defines life seems to have broader distribution as well as a long cosmic lineage%u201D, but YES "a molecular conformation dominant in Earth life may have broader distribution and additional cosmic presence.%u201D

Next, re in A above "the mystery as to why this is the case":

My conjecture about the probable reasons for the prevailing chirality:

Darwinian evolution started at life's day one, with the genesis of the first organisms, the replicating oligomers, pre-archaea genes. It started under yet-unknown energetic conditions, by a serendipitous accident, with oligomeric (RNA?) conformations, in a soup containing all their essential molecular progenitors. These Conformations happened to absorb the amounts of energy enabling their polymerization, to lengths precipitated as determined by the nature and conditions of the soup.

The sugars and the nitrogen-based compounds that, together with the phosphates, are the components of the genes-organisms, are chiral. There probably is an energetic advantage in homochirality and chiral homogeneity for the self-replication of biopolymers.

This serendipitous accident set up a matrix-field of energy with a potential extended between its source, the sun radiation and the precipitating organisms. This was the genesis of the ongoing formation and maintenance of Earth's biosphere.

And since the biosphere started it could only evolve in more favorable energetic directions and towards stabler components. Survival. After all this is evolution.

But this is a conjecture. Chirality in life still awaits elucidation...


Dov Henis