Fifty Shades of Red

Do you know why your blood is red? It’s thanks to the red blood pigment, haemin, which is one of the components of haemoglobin.

And why do I know this? Well, because I’ve been reading up on Hans Fischer, the German biochemist who was born on this day in 1881, and who was awarded the Nobel Prize for Chemistry in 1930, primarily for his work on the structure and synthesis of the blood pigment haemin. In 1929, Fischer succeeded in synthesising haemin, the deep red, oxygen-carrying, non-protein, ferrous component of haemoglobin, that gives blood its red colour.

It’s elementary, my dear Watson – this is definitely not alien blood.
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Oxygen-rich blood (such as arterial blood and capillary blood) is bright red, as the oxygen intensifies the colour in the haemin. When oxygen is extracted from the blood it turns a darker shade of red – this can be seen in the veins, and in the blood collected during blood donation. The colour of blood can also be an indicator for certain medical conditions. Both carbon monoxide poisoning and cyanide poisoning result in bright red blood, as it inhibits the body’s ability to extract and utilise the oxygen in the blood. On the other hand, severe deoxygenation (which can be caused by respiratory diseases, cardiac disorders, hypothermia, drug overdose or exposure to high altitude) results in a condition called cyanosis, where the blood darkens to such an extent that it gets an almost purple-blueish hue, resulting in the skin turning a blue colour.

While the blood of humans and all vertebrates is always a shade of red (containing haemin), it’s interesting to note that it is, in a strange way, surprisingly close to being green! In addition to his work on blood pigmentation, Thomas Fischer also studied the components of the pigments in leaves. He found that, like the haemin in blood, the chlorophyll in leaves is a porphyrin, and that haemin and chlorophyll share a very similar structure, with only subtle differences.

All of this talk of blood, and red and green pigmentation, conjure scenes of science fiction in my mind – if haemin (that makes blood red), is so similar to chlorophyll (that makes leaves green), perhaps the idea of green-blooded aliens is not such a stretch. It makes scientific sense, right?

Anyway, let me rather stop before I get too carried away. Enjoy the day, and keep an eye out for those little green men! 🙂

Artificially green – celebrating the synthesis of chlorophyll

Today seems to be one of those ordinary days in history – at a cursory glance, nothing seriously bad happened, but nothing too exciting either.

Well, I am no chemist, but the fact that chlorophyll A was for the first time synthesised in a laboratory on this day back in 1960, is probably pretty exciting. Its chlorophyll, after all – the abundant green stuff which allows plants to absorb energy from light, and through the process of photosynthesis, fuel much of our planet.

The organic chemist responsible for this achievement was Robert Burns Woodward, from the Converse Memorial Laboratory at Harvard University. For this, and his other work in the field of organic synthesis, Woodward was awarded the 1965 Nobel Prize in Chemistry.

Chlorophyll – fuelling our planet.
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Talking about synthesized chlorophyll and photosynthesis, I read an interesting 2011 Economist blog post, Babbage Science and Technology, about work being done around artificial photosynthesis and the creation of the “artificial leaf”. The science-fiction style scenario envisaged from this is a world where roofs of city buildings etc can be covered with “artificial trees” replicating the photosynthesis process to create hydrocarbon fuel directly from sunlight. These “forests” could help offset the emission of carbon dioxide from fossil fuels, and create an unlimited supply of fuel for transport – a magical concept.

In the USA, hundreds of millions of dollars are being spent in research laboratories in California etc working, in the words of President Obama, on “developing a way to turn sunlight and water into fuel for our cars”.

The potential energy produced by the sun is vast – apparently the energy from the sun hitting the earth in a single hour, exceeds all the energy consumed by humans in an entire year! Imagine if a significant portion of that energy could be harvested in a commercially viable manner. Currently solar energy (in the form of sustainable biomass) provide less that 1.5% of our energy needs, with solar panels contributing less than 0.1%.

Current solar power generators suffer from the fact that the supply of sunlight is not constant, and energy has to be stored in batteries – a wasteful process. What scientists are working on (and what chlorophyll has been quietly doing for millions of years), is to turn the sunlight directly into chemical fuel – a potentially huge paradigm shift in the harvesting of solar energy.

While scientists have already been able to efficiently create fuel from sunlight in laboratory conditions, the problem is that it cannot yet be done at an economically viable cost. The technology is also highly fragile, nowhere near the robustness required for continuous commercial implementation.

So they are looking at nature for inspiration, and more specifically chlorophyll. In the words of Babbage, “chlorophyll acts as a catalyst that drives the oxidation-reduction reaction between carbon dioxide and water to produce carbohydrates and oxygen. In the pursuit of the artificial leaf, then, the main task is to find catalysts that can mimic the intricate dance of electron transfers that chlorophyll makes possible.”

Amazing research is being conducted on this topic, creating and studying different light absorbers, chemical catalysts and membranes to support these. And interestingly, it appears one of the wild cards in this research race is a small research group from Massey University down here in New Zealand. A research team at the university’s Nanomaterials Research Centre, led by Wayne Campbell, has produced a porphyrin dye that works with solar cells based on titanium dioxide. In the lab, these cells are reported to generate electricity 10 times more economically than conventional photovoltaic panels.

I have been unable to find any information on the current status of this research (much of the published results are about 5 years old), but potentially, these porphyrin dyes can become an economically viable catalyst for producing solar fuel for cars and electricity for homes.

It’s exciting stuff, and potentially huge for a greener future (even if some of the green may be artificial)!