JOIN USA team at University of Groningen, led by Prof Bauke Dijkstra and Prof Lubbert Dijkhuizen, has claimed the findings would stimulate identification of substances that inhibit the enzyme, the 'PNAS' journal reported.
Just add that substance to toothpaste, or even sweets, and caries will be a thing of the past, say the scientists.In their study, the scientists analysed 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, bacterium Streptococcus mutans, also uses this enzyme. Once attached to tooth enamel, these bacteria ferment sugars releasing acids that dissolve the calcium in teeth. This is how caries develops.
Using protein crystallography, the researchers were able to elucidate the three dimensional (3D) structure of the enzyme. They are the first to succeed in crystallizing glucansucrase.
The crystal structure has revealed that the folding mechanism of the protein is unique. The various domains of the enzyme are not formed from a single, linear amino acid chain but from two parts that assemble via a U-shaped structure of the chain; this is the first report on such a folding mechanism in the literature.
The unravelling of the 3D 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 various inhibitors studied not only blocked the glucansucrase, but also the digestive enzyme amylase in our saliva, which is needed to degrade starch," Prof Dijkhuizen said.