Silica Particle Sparks Life In Protein

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Silica Particle Sparks Life In Protein

http://www.medicalnewstoday.com/medicalnews.php?newsid=59110

Tiny formless particles in water solution take on a well-ordered and

functional structure as soon as they come into contact with

nanoparticles of silica. A unique breakthrough by researchers at

Linkoping University in Sweden creates new potential in medicine and

biochemistry and at the same time provides a new piece of the puzzle

in theories about the origins of life.

Normally, inorganic materials like silica are unwelcome in

biological systems, since they disrupt the form and function of

proteins.

" We wanted to reverse the thinking and try to design proteins that

take on their function only after encountering an inorganic

surface, " says Bengt-Harald Jonsson, professor of molecular

biotechnology.

He directs the research team that is now presenting its findings in

Angewandte Chemie.

The team designed a peptide (a short protein) with a specific

distribution of positive charges. The peptide was mixed into a

solution of spherical silica particles, about 9 nanometers

(billionths of a meter) across. When the peptide was free in the

solution it had no structure whatsoever, but when it connected with

the negatively charged silica ball it assumed the form of a helix.

The result was a complex of a silica particle and a functional

protein.

When the researchers added amino acids to their peptide, the complex

took on the properties of a catalyst, a function similar to that of

enzymes in living cells.

The method has several possible fields of application:

-- recognition of organic molecules

-- catalyzing of chemical reactions with precise control

-- target-seeking particles for medical uses

But the Linköping University scientists' successful experiment may

also shed light on the eternal question of the origin of life.

Particles of clay containing silica in the `primeval soup' may have

attracted unstructured peptides with amino acids attached and given

rise to the first functional proteins.

" We know that RNA (which plays a decisive role in the transfer of

information in cells) can bind with clay particles whose surfaces

have negative charges. The probability of peptides with amino acids

having formed well-defined structures with the clay at an early

stage of development is considerably greater, since they are more

diversified than RNA is, " says Bengt-Harald Jonsson.

http://www3.interscience.wiley.com/cgi-bin/jissue/104540294