Exercise.
Love it or hate it, we've all got to do it.
And it's thanks to a protein called myoglobin that we can
extract oxygen from our red blood cells and store it in
our muscles.
Encoded by a gene on chromosome 22, myoglobin has a
key role in providing oxygen for the biochemical reactions
that keep us moving.
The protein also has a very significant place in the
history of 20th century science, and it all
started with this.
Here at the science museum in London is an early model of
the myoglobin molecule.
And while it may not look very impressive--
indeed, the model is rather disgusting--
it represents a landmark achievement.
This, the culmination of over 20 years' work by scientists
working in Britain, is the very first protein structure
to have been seen by humankind.
The model was built in 1958 by John Kendrew using information
collected by firing x-rays at crystals
of sperm whale myoglobin.
By measuring the pattern of spots generated as the
myoglobin crystals scattered the x-rays into many different
directions, he was able to calculate the
structure of the molecule.
This early model is relatively crude.
It only shows the overall shape of the protein.
But that's because Kendrew's first crystals
weren't very good.
But the technique, x-ray crystallography, would come to
revolutionise the way that we study biology.
And since 1958, it has allowed scientists to work out the
structures of many different biological molecules from the
enzymes that digest our food, to the ion channels that
conduct electric signals in our brains.
Today in my lab, we still use many of the same techniques
that Kendrew first applied to myoglobin.
Within a few years, he had improved his original crystals
and was able to reveal the true complexity of myoglobin's
atomic structure, unveiling its beautiful helices and the
precise arrangement of bonds between its atoms.
You can now see exactly how the protein chain falls around
the porphyrin group to create a binding site for a single
molecule of oxygen.
One of the most interesting things about this early work
was that when Max Perutz applied crystallography to
study horse haemoglobin, the molecule that transports
oxygen in red blood cells, he could see for the first time
that it was very similar in structure to myoglobin.
This showed not just the evolutionary relationship at
the molecular level between different species--
horses and whales--
but also that evolution could adapt a relatively simple
structure and give it a more complex form and function.
In fact, if you take a glance to the right of Kendrew's
model at the science museum, you'll see Max Perutz's
structure of haemoglobin, which is made of four chains,
each of which looks very like myoglobin.
From that humble, rather hideous start in 1958, it's
amazing how far we've travelled.
Over 90,000 structures of protein, DNA, and RNA
molecules have now been determined by x-ray
crystallography, giving us detailed insights into how
life operates at the molecular level.