{Reference Type}: Journal Article
{Title}: Structural insights into the catalytic reaction that is involved in the reorientation of Trp238 at the substrate-binding site in GH13 dextran glucosidase.
{Author}: Kobayashi M;Saburi W;Nakatsuka D;Hondoh H;Kato K;Okuyama M;Mori H;Kimura A;Yao M;
{Journal}: FEBS Lett
{Volume}: 589
{Issue}: 4
{Year}: Feb 2015 13
{Factor}: 3.864
{DOI}: 10.1016/j.febslet.2015.01.005
{Abstract}: Streptococcus mutans dextran glucosidase (SmDG) belongs to glycoside hydrolase family 13, and catalyzes both the hydrolysis of substrates such as isomaltooligosaccharides and subsequent transglucosylation to form α-(1→6)-glucosidic linkage at the substrate non-reducing ends. Here, we report the 2.4Å resolution crystal structure of glucosyl-enzyme intermediate of SmDG. In the obtained structure, the Trp238 side-chain that constitutes the substrate-binding site turned away from the active pocket, concurrently with conformational changes of the nucleophile and the acid/base residues. Different conformations of Trp238 in each reaction stage indicated its flexibility. Considering the results of kinetic analyses, such flexibility may reflect a requirement for the reaction mechanism of SmDG.