Researchers from the University of Groningen in the Netherlands have deciphered the structure and functional mechanism of the glucansucrase enzyme that is responsible for dental plaque sticking to teeth. This knowledge will stimulate the identification of substances that inhibit the enzyme. The researchers analyzed glucansucrase from the lactic acid bacterium Lactobacillus reuteri, which is present in the human mouth and digestive tract. The bacteria use the glucansucrase enzyme to convert sugar from food into long, sticky sugar chains. They use this glue to attach themselves to tooth enamel. The main cause of tooth decay, the bacterium Streptococcus mutans, also uses this enzyme. Once attached to tooth enamel, these bacteria ferment sugars, releasing acids that dissolve the calcium in teeth. Using protein crystallography, the researchers were able to elucidate the 3-dimensional (3-D) structure of the enzyme. The unraveling of the 3-D structure provided the researchers with detailed insight into the functional mechanism of the enzyme. The enzyme splits sucrose into fructose and glucose and then adds the glucose molecule to a growing sugar chain. The model created by the researchers has revealed that both these activities occur in the same active site of the enzyme. Specific inhibitors for the glucansucrase enzyme may help to prevent attachment of the bacteria to the tooth enamel. Information about the structure and functional mechanism of the enzyme is crucial for developing such inhibitors. Thus far, such research has not been successful. In the future, glucansucrase inhibitors may be added to toothpaste and mouthwash, and it may even be possible to add them to sweets.
(Source: ScienceDaily December 4, 2010)
