The Alchemist Newsletter: October 28, 2008

In Issue 100 of the relaunched ChemWeb Alchemist, we report on energy is top of the agenda with a record-breaking solar cell material from Australia. New insights into the ripening of bananas reveals they get the blues while crystallography has been thrown a curveball as scientists discover the active sites in many models of protein receptors are not what they seemed to be. The chemistry of alternative medicine sits toxically under the glare of the Alchemist's lamp and revelations about yet another small molecule with a crucial role to play in cellular control. Finally, a double ACS award for research on the structure and reactivity of molecular oxygen binding to copper and iron complexes, which could have future energy applications.

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Shedding light on solar cells

The first silicon photovoltaic solar cell to surpass the 25% efficiency mark has been made by researchers in Australia. Martin Green and colleagues at the University of New South Wales say they are now close to the 29% theoretical maximum for first-generation photovoltaics. The development relies to some extent on a renewed understanding of sunlight and exploits a wider range of wavelengths and a design that wastes less energy during the trapping and conversion processes.

Magic solar milestone reached

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Ripening bananas get the blues

Researchers at the University of Innsbruck, Austria and Columbia University, New York, USA, have finally explained why ripened bananas glow blue under ultraviolet, black, light. Writing in Angewandte Chemie, Bernhard Kräutler and his colleagues report that blue hue is due to the breakdown of chlorophyll, which takes place during the ethylene-modulated ripening process of the curvy fruit. In this process, colorless, but nevertheless fluorescent, degradation products become concentrated in the skin of the banana and produce an eerie glow under UV. The researchers suggest that because wild animals that eat bananas can see into the UV, this blue hue would attract them to the fruit as an indicator of it being ready to eat.

Blue Bananas

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Drug design nixed

The discovery of a supercaffeine molecule could pave the way to a novel treatment for Parkinson's disease but the studies also lay bear a flaw in targeting receptors based on conventional crystal structures. The work of Ad IJzerman and Rob Lane at Leiden University and colleagues at the Scripps Institute in La Jolla in the United States, suggests that many models used in drug design may be incorrect. In clarifying the structure of the adenosine A2A receptor for caffeine the team discovered that the active site is very different in the conventional crystal structure from that observed when the protein is crystallized in a more natural fatty environment mimicking the cell membrane. The findings could have repercussions across the field of drug design.

Coffee and Parkinson's

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Heavy metal poisons

Ayurvedic medicines can contain dangerous quantities of heavy metals, including lead, mercury, thallium and arsenic, say clinical toxicology specialists in London. Writing in the International Journal of Environment and Health, they warn that recent legislation within the European Union, which was aimed at improving safety of shop-bought products, will have little impact on medicines prescribed by traditional practitioners, those imported by individuals from overseas or bought direct over the Internet or by mail order. Heavy metals are added deliberately to many Ayurvedic "remedies" as part of the treatment which aims to rebalance the body and is claimed to treat a huge range of diseases from asthma to cancer.

Alternative medicine and heavy metal poisoning

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Smelly control molecule

Another small molecule, to add to carbon monoxide and nitric oxide has been revealed as having an important role to play in controlling biological systems in the cell. This time, Solomon Snyder of the Johns Hopkins University and colleagues have found that the "rotten eggs" smelly compound hydrogen sulfide plays a role in controlling blood pressure. H2S is produced in the thin, endothelial lining of blood vessels, the researchers found, and as the newest addition to the family of gasotransmitters, joins chemical signal molecules, including NO, CO, dopamine and acetylcholine. "Now that we know hydrogen sulfide's role in regulating blood pressure, it may be possible to design drug therapies that enhance its formation as an alternative to the current methods of treatment for hypertension," says Snyder.

If Your Systolic Stinks, “Rotten Egg” Gas May be Why

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Breath of fresh air wins two awards

Kenneth D. Karlin of the Johns Hopkins University is to receive two awards from the American Chemical Society for his work on the structure and reactivity of molecular oxygen binding to copper and iron complexes, which could have future energy applications. Karlin is the sixth chemist to receive the F. Albert Cotton Award in Synthetic Inorganic Chemistry, which will be presented at an ACS symposium in March 2009 and he has also been recognized by the Sierra Nevada section of the ACS with its 2009 Distinguished Chemist Award. Karlin's excitement for his own current research was sparked when, as a senior undergraduate at Stanford, he attended seminars led by a well-known chemist. "Scientists can be interested in so many different topics," Karlin said, "but it's when you find something that feels right, that you pursue it."

Chemistry professor's oxygen studies rewarded

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-- David Bradley, Science Journalist