Peptides May Hold 'Missing Link' to Life

[Elmore Furth]

Different schools of thought about the origin of life have several predominant themes: 1) replicators first or 2) metabolism first.

Here is a potential encapsulating mechanism for the metabolism first school.



I realize there are other competing points of view, but ...

ScienceDaily (May 7, 2010) — Emory scientists have discovered that simple peptides can organize into bi-layer membranes. The finding suggests a "missing link" between the pre-biotic Earth's chemical inventory and the organizational scaffolding essential to life.

"We've shown that peptides can form the kind of membranes needed to create long-range order," says chemistry graduate student Seth Childers, lead author of the paper recently published by the German Chemical Society's Angewandte Chemie. "What's also interesting is that these peptide membranes may have the potential to function in a complex way, like a protein."

Chemistry graduate student Yan Liang captured images of the peptides as they aggregated into molten globular structures, and self-assembled into bi-layer membranes. The results of that experiment were recently published by the Journal of the American Chemical Society.

"In order to form nuclei, which become the templates for growth, the peptides first repel water," says Liang, who is now an Emory post-doctoral fellow in neuroscience. "Once the peptides form the template, we can now see how they assemble from the outer edges."



Peptides May Hold 'Missing Link' to Life

[Cassandra]

1. Cellular peptide cake... with mint frosting

Mmmmm....

[skepticscott]

6. Delicious!

But are you going to answer that ringing?

[Cassandra]

9. Only after you hand me a straw.

;-)

[Kurt_and_Hunter]

2. I prefer replicators first

I love the clay theory! Doesn't mean it's right, but I love it.

[Warpy]

5. I'm with you

because replication would be what would afford the developing whatever it was from the environment enough to let metabolism occur, while making metabolism necessary to continue.

Still, it's one of those chicken-egg arguments that will likely never be solved until we figure out a way to date DNA components and travel back in time that way.

[Speck Tater]

3. This is very exciting.

Many years back I did a bunch of work on computer simulation of the evolution of autocatalytic sets, which those "reaction cycles" essentially are. I'm going to have to dig into this a little deeper. It's very cool stuff.

[snagglepuss]

4. For the scientifically challenged but curious DUer such as moi, a peptide is an

"Organic compound composed of a series of amino acids linked by peptide bonds (see covalent bond) between a carbon atom of one and a nitrogen atom of the next. Peptide chains longer than a few dozen amino acids are called proteins. Biosynthesis of peptides from a succession of amino acids carried by transfer RNA molecules takes place on ribosomes and is catalyzed and controlled by enzymes. Many hormones, antibiotics, and other compounds that participate in life processes are peptides."

def from Britannica Concise Ency.

http://www.answers.com/topic/peptide


Fascinating. Thanks for posting. Love the cartoon.

[eppur_se_muova]

7. Ummmm ... Google "peptide protocells"

"Early cell membranes could have formed spontaneously from proteinoids, protein-like molecules that are produced when amino acid solutions are heated–when present at the correct concentration in aqueous solution, these form microspheres which are observed to behave similarly to membrane-enclosed compartments."

http://en.wikipedia.org/wiki/Abiogenesis#From_organic_molecules_to_protocells

[bananas]

8. tongue and saliva ...

"the tongue rarely gets infected, and when it does, it usually heals quickly."
there's a lot more, but not necessarily at this link: http://www.dandydesigns.org/id54.html


edit to add: http://en.wikipedia.org/wiki/Neuropeptide