The End of Tooth Decay

Researchers at the University of Groningen have deciphered the structure and function of the glucansucrase enzyme that is responsible for dental plaque sticking to teeth. They hope that with this knowledge they can develop an enzyme inhibitor that will prevent the bacteria from attaching to teeth. The professors, Bauke Dijkstra and Lubbert Dijkhuizen published their findings in the journal Proceedings of the National Academy of Sciences (PNAS).

The researchers obtained the enzyme from the lactic acid bacterium Lactobacillus reuteri, which is present in the human mouth. The bacteria use glucansucrase to create long, stick sugar chains which attach them to the tooth enamel. Streptococcus mutans, the main cause of tooth decay, attaches itself to the teeth with this enzyme’s product and then ferments sugars which release acids that dissolve the calcium in teeth. The enzyme specifically works by splitting sucrose into fructose and glucose and adding the glucose to a long growing sugar chain. These processes are performed by the same active site of the enzyme, giving more hope for the discovery of an inhibitor.

The researches were the first to successfully crystallize glucansucrase and see its #D structure. They discovered that the enzyme isn’t formed by a single linear amino acid chain, but from two parts that assemble via a U-shaped structure of the chain. This is notably the first report on such a folding mechanism.

The prime goal of the research is to develop an inhibitor that specifically blocks glucansucrase. The problem that the research team has developed is that glucansucrase seems to have evolved from amylase, another enzyme humans have in their mouths. Dijkhuizen says, “The various inhibitors studied not only blocked the glucansucrase, but also the digestive enzyme amylase in our saliva, which is needed to degrade starch.” Because the active sites are almost identical, further research will need to be done to develop an inhibitor that only blocks the glucansucrase enzyme. Dijkhuizen points out that in the future, such an inhibitor could be added to mouthwash or toothpaste.

I found this article to be interesting I am interested in going to Dental school and this research has huge implications on the Dental field. In the past I had heard of research being done to modify bacteria in the mouth to produce alcohol as a waste product in order to reduce tooth decay. It is also interesting that such a damaging enzyme could develop from an essential one: amylase. Finally, I also find articles interesting that explain how the molecular level of structure leads to the macroscopic function. Like in this article, the linking of glucose molecules creates a “glue”, that lets bacteria bind to tooth enamel.

Article Source: http://www.sciencedaily.com/releases/2010/12/101203101341.htm
Alexander J. Quante '13 -- VTPP 435