Bruce Bryan demonstrated a glowing cocktail drink (top left), and tempted us with fluorescent cake frosting (top right). The chocolate surprise boxes included a lollipop (bottom left) and I was quite busy sucking the lollipop, listening to the translation of the Belgian/French/Spanish contributions, taking notes and photographing at the same time (bottom right).

The chocolate surprise box was one of the highlights at The Flemish Primitives that I’ve blogged about three times already. As I promised you in the last post I’d come back to the lollipop that was included in the box. Between chocolates number 2 and 3 Bruce Bryan entered the stage. The lights went off, we were instructed to suck intensely on the lollipos and then – when I took the lollipop out of my mouth it was glowing! I was sitting in the front row, but as I turned around I saw a fully packed auditorium of people sticking out their glowing tongues and holding a glowing lollipop in their hands. The only sound you could hear was a whispering choir of “wows”. That was quite amazing!

Bruce Bryan is a medical doctor by profession but he now spends most of his time trying to secure funding for his inventions related to bioluminescence. His primary invention is related to the use of green fluorescent proteins in combination with luciferin/luciferases as tumor markers by combining them with appropriate antibodies. I’m not able to explain the details, but you can find more information on Bruce’s homepage. The take home message is that it for instance can improve cancer surgery by litterarily being a “guiding light” for the surgeon.

Bioluminescence is emission of light by living organisms. Glow worms (which include Fire flies) and dinoflagellates are among the best known. Most dinoflagellates are marine plankton and they glow when the water is disturbed, for instance by waves crushing onto the shore or by the propeller of an outboard motor. Sitting in a small motorized boat, crusing through water that is glowing is truly amazing – I got to experience this some years ago! And the chemistry behind is also fascinating – I’ve included a little about that at the end of the post.

A lollipop submerged in a glass with hot water which makes it glow even brighter (yet still requiring 8 seconds of exposure time!).

I had a quick chat with Bruce Bryan in the break following his presentation and he was so kind to give me two lollipops to take home. Of the glowing kind, yes. That’s how I got the pictures in this post. He suggested that I hold a lollipop under hot running water and then spray the water clinging to the lollipop on a wall in a dark bathroom. – You’ll see the universe open up in front of you, Bruce told me enthusiastically. I tried it and you can see a picture below.

Unfortunately it has been hard to find funding for further development and FDA approval of the isolated luciferin/luciferase complexes of use in food. In fact, during his presentation Bruce showed us a slide with the following text:

(…) These “colorants” are not FDA approved and may not be by the patent expiration (10 years) if some broader shoulders don’t get involved. Optimistic estimates are 2 1/2 years and $5 million dollars to get these products approved. (…) we’ve cloned six genes, spent a lot on collection, have put our life savings and mortgages into making rapid chip based diagnostic and cancer imaging applications possible! Tragically we have not had ANY corporate interest.

Considering this it might be true what he jokingly said about the lollipops perhaps being the most expensive candy ever made Even ideas such as “Bud light” or “Pepsi light” (yes, that kind of light) were turned down by the respective companies. The only products to appear so far are various toy items which are available online through Biotoy. Bruce has also set up the companies Prolume, Biolume and Nanolight to further develop and market the technology. His own homepage also has some info and the full text of the patents is easily found with a google search.

The lollipops (top left) I got from Bruce were of a different kind than those in the chocolate surprise box. A nice “stars of the universe” effect was achieved by dipping the lollipop in water and spraying the bathroom wall (top right). The bottom pictures shows my glowing tongue and the lollipop (sorry for the blurry picture – exposure time is 1 second at ISO 1600).

The chemistry behind the glowing lollipops is fascinating. What is required is a luciferin and luciferase. These are not specific compounds but rather generic terms. Luciferin is a compound which acts as a substrate for the reaction that generates light (see list of luciferins) and luciferase is an enzyme which catalyzes the reaction. One of the most common luciferins is coentelerazine (shown in the figure below). In the presence of a suitable luciferase and oxygen it is oxidized to coenteleramide. The important thing here is that coenteleramide exists in an excited (energy rich) state. To get rid of the excess energy it emits a photon which we see as light. In the process the substrate (or fuel if you like) is used up and must be provided continously for constant light production. The enzyme luciferase is unchanged by the reaction and can be reused. Further information on coelenterazine chemistry and bioluminescence can be found in the book “Bioluminescence” by Osamu Shimomura who was awarded the 2008 Nobel prize in chemistry (together with Martin Chalfie and Roger Tsien) for the discovery of green fluorescent protein.

In the presence of a luciferase and oxygen coentelerazine is oxidized to coenteleramide in an excited state. As coenteleramide reverts back to it’s ground state it emits light. The part of the coentelerazine molecule where the changes occur is indicated with blue color. The cartoon representation of luciferase is taken from Wikimedia Commons.

Update:
Bruce Bryan generously sent me a pack of different glowing candies and lollipops with different tastes and colors. IMO this surely has a market potential!

The label of the green and white lollipops reads: “Ingredients: Sucrose, corn Syrup, Tapioca & Chicory root starch, salt, natural and artificial flavors, 5 mg Renilla Luciferase protein and less than 0.2 mg Coelenterazine a naturally occurring anti-oxidant found in many fish”

As shown in the figure, the radical reacts with sulfur containing proteins, thereby forming a thiol called 3-methylbut-2-ene-1-thiol or just MBT for short. The amazing thing about this compound is that we can smell it at concentrations as low as a few parts per billion (ppb). The perhaps not-so-amazing thing is that this compound gives beer a “skunky” aroma. Obviously one would want to avoid this, and that’s why beer is sold in dark brown glass bottles that act as the beer’s own sunglasses. Canned beer of course will not go skunky (well not until it’s poured into a glass and served outside in bright sunlight – that will turn any beer skunky within minutes).

Unfortunately however, not all beer is sold in dark bottles! One well known brand is shown in the picture below…

And yes – as you might have figured out, 3-methylbut-2-ene-1-thiol is present in Corona beer (and other brands sold in clear bottles, to a lesser extent MBT is also found in green bottled beer). For some references to “skunky” off flavours in beer check out these links: here, here and here. The ubiquitious slice of lime served with Corona beer is nothing but clever marketing since it helps camouflage the smelly thiol formed! (but how well does lime actually camouflage the thiol aroma?)

The take home message is: keep your olive oil, milk, butter and beer away from sunlight!