Sunday 19 May 2013

A Sweet Birthday Tribute

I’m a day early with the next Molecule of the Week, but I have a very good reason. Today is the birthday of my featured chemist, Dr. Carolyn Bertozzi of the Lawrence Berkeley National Laboratory in California.

As my birthday tribute to her I have chosen a chemical likely to be found in her birthday cake, a chemical which has also played an important part in her scientific career – glucose. This is a representative example of one of the sugars and sugar compounds that go to form glycans, complex molecules which attach themselves to cell membranes.

For the past few years Carolyn Bertozzi has been at the forefront of a new field in biochemistry. So new, in fact, that it didn’t have a name until Caroline invented one for it – bio-orthogonal chemistry. In contrast to the methods Jay Keasling developed to produce a synthetic malaria drug (by altering the DNA of bacteria to make them produce the drug), Carolyn’s work uses chemistry to detect the way cells communicate with and recognise other living cells (without changing the DNA).

Glucose is one of the natural sugars which form these complex molecules called glycans. They attach themselves to protein or fat molecules in cell membranes and are able to detect whether the cell is working okay or is under attack from a virus or bacteria. The cell can send chemical messages to it’s neighbours to tell them to alert the immune system. The immune system in animals and humans relies on body cells (such as white blood cells) which recognise diseased or infected cells. By recognising these cells, antibodies are produced. Naturally, the thought of HIV and cancer treatments also comes to mind. In transplants these cells recognise the new organs as benign and reduce the risk of tissue rejection.

The principal behind bio-orthogonal chemistry is that scientists can tag specific glycans with another chemical to see which message they are sending to other cells. The tags work without effecting the natural biological processes in the living cells. If scientists know which glycans can recognise damaged or diseased cells they are able to detect diseases before they become detectable by current means, before the disease spreads to other cells. And by knowing which glycan passes on the diseased message you can deliver a glucose or sugar-based glycan to counter the signal and stop it from spreading.

Carolyn has won many professional awards for her bio-orthogonal work, including the 2007 GLBT Scientist of the Year from the National Organisation of Gay and Lesbian Scientist and Technical Professionals. Part of the citation of the award reads: “Dr. Carolyn Bertozzi has been chosen to receive the … award because of her outstanding achievements in applying chemistry to help answer biological questions related to human health and disease. Her laboratory group at the UC Berkeley studies cell surface interactions in the areas of cancer, inflammation and bacterial infection… As an open and out lesbian in academia and science Dr. Bertozzi has been an excellent role model for her students and colleagues.”

Happy Birthday Dr. Bertozzi.

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