Enzymes are proteins that accelerate, or catalyze, chemical
reactions.
In these reactions, molecules called substrates are converted by
enzymes into different molecules called products. Almost all
processes
in the cell need enzymes in order to occur at significant rates.
Like
all catalysts, enzymes work by providing an alternative path of lower
activation energy for a reaction and dramatically increasing its
rate;
some enzymes can make the conversion of substrate to product occur
many millions of times faster. Enzymes are not consumed in chemical
reactions, nor do they alter the equilibrium of a reaction. However,
enzymes do differ from most other catalysts by being much more
specific. Since enzymes are extremely selective for their substrates
and speed up only a few reactions, the set of enzymes made in a cell
determines which metabolic pathways occur in that cell. Many drugs
and
poisons work by inhibiting enzyme activity.
Read the rest of this article:
http://en.wikipedia.org/wiki/Enzyme
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Today's selected anniversaries:
1850:
The University of Sydney, Australia's oldest university, was
established in Sydney.
(
http://en.wikipedia.org/wiki/University_of_Sydney)
1865:
The Morant Bay rebellion, led by Paul Bogle and George William Gordon,
began in Jamaica and was brutally suppressed by Governor Edward John
Eyre.
(
http://en.wikipedia.org/wiki/Morant_Bay_rebellion)
1899:
The Second Boer War erupted in South Africa between the United Kingdom
and the Boers.
(
http://en.wikipedia.org/wiki/Second_Boer_War)
1954:
Ho Chi Minh and the Viet Minh took control of North Vietnam.
(
http://en.wikipedia.org/wiki/Viet_Minh)
1968:
NASA launched Apollo 7, the first manned mission of the Apollo
program.
(
http://en.wikipedia.org/wiki/Apollo_7)
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Wikiquote of the day:
It takes courage to love, but pain through love is the purifying fire
which those who love generously know. We all know people who are so
much afraid of pain that they shut themselves up like clams in a
shell
and, giving out nothing, receive nothing and therefore shrink until
life is a mere living death. -- Eleanor Roosevelt
(
http://en.wikiquote.org/wiki/Eleanor_Roosevelt)