All organic chemists are familiar with the stereochemical notation for bonds, as shown below. But I had difficulty tracking down when it was introduced, and by whom. I offer a suggestion here, but if anyone reading this blog has got a better/earlier attribution, please let us know!
Posts Tagged ‘Derek Barton’
Most scientific theories emerge slowly, over decades, but others emerge fully formed virtually overnight as it were (think Einstein in 1905). A third category is the supernova type, burning brightly for a short while, but then vanishing (almost) without trace shortly thereafter. The structure of DNA (of which I have blogged elsewhere) belongs to the second class, whilst one of the brightest (and now entirely forgotten) examples of the supernova type concerns the structure of proteins. In 1936, it must have seemed a sure bet that the first person to come up with a successful theory of the origins of the (non-random) relatively rigid structure of proteins would inevitably win a Nobel prize. Of course this did happen for that other biologically important system, DNA, some 17 years later. Compelling structures for larger molecules providing reliable atom-atom distances based on crystallography were still in the future in 1936, and so structural theories contained a fair element of speculation and hopefully inspired guesswork (much as cosmological theories appear to have nowadays!).
Science is about making connections. Plenty are on show in Watson and Crick’s famous 1953 article on the structure of DNA (DOI: 10.1038/171737a0), but often with the tersest of explanations. Take for example their statement “Both chains follow right-handed helices“. Where did that come from? This post will explore the subtle implications of that remark (and how in one aspect they did not quite get it right!).
One of the (not a few) pleasures of working in a university is the occasional opportunity that arises to give a new lecture course to students. New is not quite the correct word, since the topic I have acquired is Conformational analysis. The original course at Imperial College was delivered by Derek Barton himself about 50 years ago (for articles written by him on the topic, see DOI 10.1126/science.169.3945.539 or the original 10.1039/QR9561000044), and so I have had an opportunity to see how the topic has evolved since then, and perhaps apply some quantitative quantum mechanical interpretations unavailable to Barton himself.
The diagram below summarizes an interesting result recently reported by Hanson and co-workers (DOI: 10.1021/jo800706y. At ~neutral pH, compound 13 hydrolyses with a half life of 21 minutes, whereas 14 takes 840 minutes. Understanding this difference in reactivity may allow us to understand why some enzymes can catalyze the hydrolysis of peptides with an acceleration of up to twelve orders of magnitude.