Strawberry red, tangerine orange, banana yellow, honeydew green and plum purple. These are some of the cheesy names for the glowing molecules that were developed in Roger Tsien’s laboratory. To be fair, these names do make one thing clear: Roger Tsien has managed to design and produce fluorescent molecules of almost every colour in the rainbow.
Some might wonder why creating glowing molecules would earn someone a Nobel prize. Does the world really need more different coloured glow-sticks? Yes, of course it does! Plus, fluorescent molecules have become a standard tool in the biologist’s toolbox. Biologists tack these glowing molecules to proteins, so that they can track where in the cell it is located, or where in the body a certain genes is expressed.
Tsien gave plenty more examples of interesting applications. Neuroscientists use them to make stainings of individual neurons, generating wonderful images that are known as brainbows, for obvious reasons. Behind this neuronal extravaganza lies an ingenuous system. Every neuron expresses a random set of fluorescent proteins, so that each cell ends up being a different colour.
Tsien also described how fluorescent molecules could play a role in surgery (after calling translational research a ‘thin veneer of clinical relevance’). If you could somehow stain a tumor with one colour, and the surrounding, healthy tissue with another, a surgeon could cut away the tumour without causing excessive damage.
Tumor cells tend to produce more proteases, proteins that can cut other proteins, than healthy cells. The molecules that Tsien has designed exploit this property. His dye has to be cut by a protease, before it becomes visible on MRI images. The tumor cells ‘tear of the wrapping paper’, as Tsien called it.
When Tsien describes ‘his’ molecules, he does so with fondness. For Tsien, designing molecules is the molecular equivalent of sculpting. No two sculptors will ever create the same sculpture. Likewise, no two chemical engineers will design the same molecule. Science is often portrayed as cold and methodological, but this comparison shows that at its heart, science is a creative enterprise. Tsien felt comfortable with this creative aspect of chemistry, because it meant that he didn’t need to concern himself with the direct competition from other labs
“Pretty colours and their chemistry have fascinated me from my childhood onwards”, Roger Tsien said earlier in his lecture. I’m sure that Roger Tsien the child would have been thrilled to see the rainbow of fluorescent molecules that his older self has created.
Image credit: Jeff Lichtman