LAUSR

BT_3567 protein, a putative β‐glucosidase from Bacteroides thetaiotaomicron, exhibits higher activity toward Sop3–5 (Sopn, n: degree of polymerization of β‐1,2‐glucooligosaccharides) than toward Sop2, unlike a known β‐glucosidase from Listeria innocua which predominantly prefers Sop2. In the complex structure determined by soaking of a D286N mutant crystal with Sop4, a Sop3 moiety was observed at subsites −1 to +2. The glucose moiety at subsite +2 forms a hydrogen bond with Asn81, which is replaced with Gly in the L. innocua β‐glucosidase. The Km values of the N81G mutant for Sop3–5 are much higher than those of the wild‐type, suggesting that Asn81 contributes to the binding to substrates longer than Sop3.