Fig. 4: Characterization of the pseudoglycosyltransferase AcbS.
From: Complete biosynthetic pathway to the antidiabetic drug acarbose
a ESI( + ) EIC for acarbose at m/z 646.2553 of reaction mixtures with AcbI, AcbQ, or with or without AcbS; b ESI-MS/MS of the AcbS product; c ESI-MS/MS of acarbose standard; d reaction scheme of AcbR and AcbS; e ESI( + ) EIC for acarbose at m/z 646.2553 of reaction mixtures with AcbI, AcbR, and AcbS added in different sequence and combination (see text and experimental section). All experiments were carried out at least three times with similar results. ESI, electrospray ionization mass spectrometry; EIC, extracted ion chromatogram; V1P, valienol 1-phosphate; GDP-V, GDP-valienol; dTDP-4a6dGlc, dTDP-4-amino-4,6-dideoxyglucose; 4-aminoDGG, O-4-amino-(4,6-dideoxy-α-D-glucopyranosyl)-(1→4)-O-α-D-glucopyranosyl-(1→4)-D-glucopyranose.
