 ESSENTIAL REACTIONS TOO SLOW FOR LIFE, according to a report in Biology News
Net, 11 Nov 2008. Most chemical reactions inside living
cells are controlled by enzymes that speed up the rate of reaction. Without
the enzymes the reactions would not occur fast enough
to sustain life. Richard Wolfenden, a biochemist at the University of North
Carolina at Chapel Hill, has been studying chemical
reactions that are essential to life to see how they would work without the
enzymes. In 1995 he worked out that a reaction
absolutely necessary for making DNA and RNA would take 78 million years
without the enzyme that makes it happen in living cells.
Now he and a colleague have "found a reaction that - again, in the absence
of an enzyme - is almost 30 times slower than that. Its
half-life - the time it takes for half the substance to be consumed - is 2.3
billion years, about half the age of the Earth. Enzymes
can make that reaction happen in milliseconds." The reaction is essential
for making chlorophyll and haemoglobin (green pigment in
plants, red pigment in blood). Wolfenden commented: "This enzyme is
essential for both plant and animal life on the planet. What
we're defining here is what evolution had to overcome, that the enzyme is
surmounting a tremendous obstacle, a reaction half-life of
2.3 billion years." Understanding how chemical reactions and their enzymes
work is important for developing new medicinal drugs,
but man-made enzymes are a long way off, according to Wolfenden. He said:"We've only begun to understand how to speed up reactions
with chemical catalysts, and no one has even come within shouting distance
of producing, or predicting the magnitude of, their
catalytic power."
Biology News Net:
http://www.biologynews.net/archives/2008/11/11/without_enzyme_biological_reaction
_essential_to_life_takes_23_billion_years.html
ED. COM. The enzyme required for this reaction is only one of thousands
necessary to make the simplest cell function. Even if most
of these reactions don't have a natural reaction time nearly as slow as the
one described above, they are far too slow to make life
without enzymes to speed them up. Enzymes are large complex proteins, made
by linking many hundreds of amino acids that must be put
together in a specific sequence. This only happens in cells because
information from DNA is used to determine which amino acids
goes in which place in the chain. Furthermore, chemical reactions in cells
do not occur in isolation. They work in complex series
of reactions, which must work in the correct sequence and have their rates
coordinated. This often involves other chemicals called
co-enzymes that must be in the right place at the right time. Altogether, it
requires the most enormous faith in something we have
never seen happen to believe that a living cell could form itself from
uncontrolled chemical reactions. It also requires faith to
believe that living cells were created, but this is a rational faith,
because we have seen reaction controlling catalysts created by
intelligent scientists. Therefore, it is reasonable to believe the more
efficient catalysts in living cells were designed and made
by a much smarter biochemist. (Ref. Time biochemistry, biosynthesis)
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