Unlocking the Hydrolytic Mechanism of GH92 α‐1,2‐Mannosidases: Computation Inspires the use of C‐Glycosides as Michaelis Complex Mimics

The conformational changes in a sugar moiety along the hydrolytic pathway are key to understand the mechanism of glycoside hydrolases (GHs) and to design new inhibitors. The two predominant itineraries for mannosidases go via (O) S (2)→B (2,5)→(1) S (5) and (3) S(1) →(3) H (4)→(1) C (4). For the CAZy family 92, the conformational itinerary was unknown. Published complexes of Bacteroides thetaiotaomicron GH92 catalyst with a S‐glycoside and mannoimidazole indicate a (4) C (1)→(4) H (5)/(1) S (5)→(1) S (5) mechanism. However, as observed with the GH125 family, S‐glycosides may not act always as good mimics of GH's natural substrate. Here we present a cooperative study between computations and experiments where our results predict the E (5)→B (2,5)/(1) S (5)→(1) S (5) pathway for GH92 enzymes. Furthermore, we demonstrate the Michaelis complex mimicry of a new kind of C‐disaccharides, whose biochemical applicability was still a chimera.