Monday, July 21, 2008

Of Wine and Chemistry

I was away at a conference last week. One of those great small conferences where you can spend a lot of time interacting with people outside of the talks. It was great. I'm convinced the best science is discussed over beer and wine. I titled this blog post Wine and Chemistry because I like wine. It's not that I don't like beer. I do. I just can't drink very much of it before I feel bloated and uncomfortable. Thus I much prefer a nice red wine to drink while pondering the deeper aspects of asymmetric catalysis. I am not alone in this. Some friends of mine who were also at the conference are wine lovers and we had a nice little private wine tasting one evening. It was a wonderful experience as I got to taste a wine that was over 40 years old. The cork you see above is from that special bottle of Rioja. Although it was delicate and it broke when we pulled it from the bottle, it was in surprisingly good shape. The wine, on the other hand, was about 20 years past its prime. Not spoiled but it definitely was flat. It tasted like compost. That brings me to a little bit of chemistry. The wine was definitely oxidized but was not vinegar. It was stored well and the closure held up against the ravages of time. It was almost sherry like. Of course the one thing that distinguishes an oxidized wine like sherry is the presence of acetaldehyde. This had quite a bit of it. The tannins were completely gone. I wonder if there was any resveratrol left? Definitely not a wine I would pop and pour at a picnic but it was truly an experience to taste history.

Friday, July 11, 2008

Largazole and Histones

I have a certain affection for things that affect epigenetic regulation. Hence my interest in a class of enzymes called histone deacetylases (HDACs). These are zinc-dependent hydrolases that cleave the acetate group off of the lysine residues on the N-terminal tails of H3 histones. The bottom line is that deacetylation of these proteins that DNA wraps around turns off gene expression. In some cancers, tumor supressor genes are turned off and application of HDAC inhibitors turns them back on causing the cancer cell to die its normal death. That is a simplistic description. It is actually much more complicated than that. A simple animation of this is provided on the Methylgene web site.

In January, the Luesch group from Florida reported (J. Am. Chem. Soc., 130 (6), 1806 -1807, 2008. 10.1021/ja7110064) the isolation and characterization of an antiproliferative natural product called largazole. They subsequently synthesized it and discovered it was an inhibitor for HDACs (J. Am. Chem. Soc., 130 (26), 84558459, 2008. 10.1021/ja8013727). The synthesis is pretty efficient encompassing 8 steps with an overall yield of 19%. That's not too bad. Andy Phillips, in Colorado, has just published another 8 step synthesis and have confirmed the Leusch findings (Org. Lett., ASAP Article, 10.1021/ol8013478 ). In addition they have done some NMR conformational studies to show the solution structure of this interesting molecule.

What I find very interesting about this story is that the compound looks so very similar to cyclic peptide HDAC inhibitors developed in Japan (FK228, link to PDF). The sulfur gets buried into the active site pocket to bind the catalytic zinc while the cyclic structure binds to the surface of the enzyme. Both are necessary for the nanomolar level of inhibition of Class I HDACs that are observed for these compounds. Knowing the structure of FK228, I would have immediately made the connection between largazole's antiproliferative effects and HDAC inhibition. The original isolation paper does not speculate on that which makes me wonder if the Leusch group only made this connection later. I presume so.

The way this story has unfolded reminds me that I need to search more broadly when I am looking for HDAC inhibitor structures. Just searching on the keyword 'hdac inhibitor' is not enough and probably misses some compounds that people haven't yet connected to HDACs.

Thursday, July 10, 2008

Atomic Noodles

Ok, I hear the voices from my last post and have decided to commit to trying to keep this blog going. My goal is to make sure I publish a post at least every week, if not more often. I've realized it doesn't have to be a chore and that I don't have to always have some latest greatest chemistry from the just uploaded ASAP's. I can do some fun stuff. I can even borrow from other stuff on the web. Why not? People do that all the time on their blogs.

Ok, then. How about a little bit of video? I know it's not directly chemistry, but it does fascinate me. From "The Ring of Truth: Atoms," here is Chef Kin Jin Mark pulling noodles.

Saturday, July 5, 2008

To be or not to be

Oh, I know I've been ignoring this blog. I wondered if anyone even read it. It has dropped down on my list of priorities. But now I read over at Homebrew and Chemistry that my blog is being chopped from at least one person's reading list. I suppose I should have seen it coming. The question is, will this inspire me to reinvigorate Carbon Tet or should I let it die in quiet peace? Perhaps if people leave a comment or two it might help me make up my mind.