moleculeoftheday | February 15, 2008Aflatoxin is a toxin produced by certain funguses that acts on the liver:
The asperilligus strains that express aflatoxins (this is a broad class of molecules; the one above is aflatoxin B1) grow on lots of different crops. Your peanut butter certainly contains some. Fortunately, people are one of the hardiest species as far as aflatoxin exposure, and that PB&J is more a concern for someone with impaired liver function.
moleculeoftheday | February 14, 2008Biotin is just a vitamin to most of us. To a lot of biologists, though, it plays the unlikely role of some of the strongest glue around.
There are proteins known as avidins that bind biotin so strongly that it's pretty much irreversible. If you stick biotin on something you're interested in, and stick avidin on a solid surface, you've pretty much got a molecular glue that's not going anywhere.
moleculeoftheday | February 12, 2008I have a lot of sympathy for graphic designers. For every one preaching to you about how you can't possibly appreciate whitespace on the same level she does, there's nine out there slogging away doing honest work. The ones who are just trying to convince the guy with the mattress store not to put seven fonts on the flyer (that's how many that are on MSNBC as I write this; you see how it's an uphill battle).
Chirality is easy to get wrong. Connectivity errors are a little rarer; usually designers seem to realize moving one of those lines in a stick figure might do something bad. However, the…
moleculeoftheday | February 8, 2008Certain derivatives of coumarin called psoralens have the effect of sensitizing you to the sun. This can be useful for treating certain skin conditions with psoralen plus a little UV lights. It can also get you really, really tan. The downside of psoralen+UV is that it's riskier skin cancer-wise than UV alone.
In the go-go 50's, however, a man named John Howard Griffin was cavalier enough to use a psoralen to get really, really tan. Tan enough that he could pass for black and write a book about his experiences in the deep south called Black Like Me. The book is one of the seminal works about…
moleculeoftheday | February 5, 2008As I've mentioned before, I'm a booster for DNA G-quadruplexes as drug targets. While telomeres might not be the best target, there are lots of potentially oncogenically relevant quadruplexes. Here is the only quadruplex-targeting antineoplastic that's made it into the clinic that I know of.
Quarfloxin, predictably, has a large aromatic surface area and a chirally disposed positive charge - perfect for targeting a groove or loop. It has shown great promise in early clinical work (it's currently in phase II) - I am rooting for the class!
moleculeoftheday | February 4, 2008Ammonia, or NH3, is a mildly toxic gas (but not that bad - you use it in metabolism). Go down one, though, and you get more lavishly toxic.
Phosphine, or PH3, is much more toxic (go down another, to arsine, and you've got another toxic beastie). Phosphine is used in fumigation for this very reason.
Going down a group will reliably get you the bizzaro version of most chemicals. Methane, CH4, is an inert, flammable gas - silane, SiH4, isn't just flammable. It'll burn without any ignition source, going up in a puff of sand - thats right, not a whoosh of CO2 - SiO2 is the solid stuff sand and…
moleculeoftheday | February 1, 2008125 years ago, a physiologist named Sidney Ringer discovered that a solution of saline prepared by his assistant seemed to keep excised rat hearts beating longer than normal saline.
It turns out this is because the assistant was a lazy slob and used London tap water instead of distilled. Good thing, too - the water, being hard, had a substantial amount of Ca2+, which we now appreciate is important in muscle function.
A derivative of the solution (invented only 50 years later) still lives on, Ringer's Lactate.
moleculeoftheday | January 30, 2008This one always shocks people the first time they hear it. Have you ever seen "carmine" on an ingredients label of some food in the red-purple color family? Yeah, you're eating bugs.
Carminic acid is extracted from the shells of certain insects.And you're not necessarily safe if it doesn't say "carmine" - it can hide behind that glib reassurance, "natural ingredients" - which the food manufacturer is using in the first place because we started fretting over artificial coloring!
moleculeoftheday | January 29, 2008After this weekend's discussion of chirality in advertising, I figured I'd post an interesting, more rigorous example of chirality. Most chiral (left- or right-handed)molecules have "asymmetric" carbons, or ones with all different things attached.
Helicene, by contrast, has none. However, it's got a twist that imparts chirality to it. Think of a left- and right-handed staircase. This, in itself, constitutes chirality - for example, DNA (almost always) twists right. If you put left-handed DNA in ads for your biotechnology company, scientists will make fun of you.
moleculeoftheday | January 26, 2008Even in cosmetics.
The scientific tour de force doesn't stop there; they also give you lessons on deuterium oxide, fullerenes, and liquid crystals.
The deuterium oxide thing is puzzling - another cosmetics company purports to sell spritzers of D2O. It's almost enough to make you buy some just to stick in the NMR to see if they're for real.
moleculeoftheday | January 25, 2008The previous entry on raspberry ketones got me thinking about supplements in general. For the most part they don't cause people problems - which is pretty remarkable, considering a lot of them do have real druglike molecules in them. Most people are taking these completely unsupervised, with only a label to guide them.
There's lots of toxic stuff in plants, too, though. One such compound is oxalic acid, which plants tolerate fine, mammals less so.
The big problem with oxalate is that it does a great job coordinating divalent metal cations, making insoluble complexes. Calcium oxalate can…
moleculeoftheday | January 23, 2008I have to admit, I am a sucker for common names. Why would you grab a bottle of mercury (II) chloride when you could get some "corrosive sublimate"? 3-methylindole? No thanks, give me skatole (named for its smell!). Methyl tert-butyl ketone? Pinacolone (which, sadly, smells like mint). 1,8-bis(dimethylamino)naphthalene? Proton sponge! (R)-2-(4-methylcyclohex-3-enyl)propane-2-thiol? Grapefruit Mercaptan!
Common names make what we do feel more like making potions, and sometimes I'm all for that.
Raspberry ketone is in that vein - it has the above systematic name. Of course, it smells like…
moleculeoftheday | January 21, 2008Everyone knows that many organic solvents won't mix with water (or, more generally, some polar solvents won't mix with some nonpolar solvents). What you might not know is that some highly fluorinated liquids aren't very polar at all, but they won't dissolve in water or many organics.
In fact, you can mix certain organic solvents, the fluorous stuff, and water, and end up with three phases! The company in that link has made a business of using perfluorinated tags to stick on your molecule, which in turn stick to a perfluorinated solid support (you later wash off your stuff with something that…
moleculeoftheday | January 17, 2008Lead and chromium (VI) - you can't do much better for toxicity.
The lead (II) salt of chromium (VI) oxide gives a vivid yellow. Before organic dye technology became robust, we were stuck with metal salts for color. This means metals. Unfortunately, there are more toxic metals than nontoxic metals, so you were stuck in a tough place there - especially if you wanted to make, say, a yellow baby rattle.
moleculeoftheday | January 15, 2008A few months ago, a group published a report that this polyamine was an effective quadruplex ligand, inducing senescence of cancer cells.
It's perhaps unsurprising that this works. I've previously covered Telomestatin (more selective) and TMPyP4 (less selective), but man, just a big charged chain of stuff? Apparently, though, this molecule is used in vivo already, in chelating copper ions in the treatment of Wilson's disease.
moleculeoftheday | January 14, 2008I love the story of valproate. About fifty years ago, an investigator was using a fatty carboxylic acid as a delivery vehicle for antiseizure medications. He looked at it alone in controls and, lo and behold, it was a drug on its own:
It's a humbling reminder to anyone who's ever designed a drug: we are not as S-M-R-T as we think we are.
moleculeoftheday | December 27, 2007Everyone by now has tried products like OxiClean, or detergents with "oxygen bleach." Rather than sodium hypochlorite, which is found in regular bleach, they've got sodium percarbonate, which is actually a mixed crystal of sodium carbonate (the old-timey name of which is "washing soda") and hydrogen peroxide. In solution, they form a "peracid," peroxymonocarbonate.
Speaking very generally, a bond between two electronegative atoms is the business end of an oxidant - the oxygen-oxygen bond in hydrogen peroxide and peroxymonocarbonate does the job there, and the oxygen-chlorine bond is the…
moleculeoftheday | December 19, 2007But if you've never read it, check out Can a Biologist Fix a Radio?
moleculeoftheday | December 18, 2007Mutual funds are such a common instrument, it's hard to imagine they were once a novel concept. In 1924, $10M were invested in US mutual funds. In 1964, $35B were invested. Skip ahead to today and the number is $12T - that's $12 x 1012. Such logarithmic growth is due to boosters like Jack Dreyfus (and more robust securities laws) bringing mainstream these newfangled "mutual investment funds," as this credulous Life Magazine profile describes them.
What, then, does Jack Dreyfus have to do with chemistry? You see, this Wall Street titan had a favorite molecule.
Phenytoin was discovered a…
moleculeoftheday | December 14, 2007Making biomolecules is tricky - getting a reasonable quantity of whatever DNA or protein you're after can take what seems like heroic efforts. You're made acutely aware of the fact that the humblest bacterium does this without breaking a sweat. Protecting and activating groups are needed, like DMT and phosphoramidites for DNA.
Dicyclohexylcarbodiimide is an activator used in making peptides.