Glucansucrases are relatively large (-160 kDa) extracellular enzymes produced by lactic acid bacteria. Usingsucrose as a substrate they synthesize high molecular mass glucose polymers, called a-glucans, which allow the bacteriato adhere to surfaces and create a biofilm. The glucan polymers are of importance for the food and dairy industry asthickening and jellying agents. An overview is given of the current insights into the structure and functioning of theseand related enzymesKeywords: glucansucrase; amylosucrase; crystal structure; catalysis; catalytic mechanism.PACS: 87.l7.Uv. B. W. Dijkstra and A. VujiCi6-ZagarLaboratory of Biophysical Chemistry, University ofGroningenNijenborgh 4,9747 AG Groningen, The Netherlands
