Scheme 3. PmST1 M144D-mediated one-pot two-enzyme (OP2E) sialylation of O-sulfo analogues of Lewisx. Yields obtained for O-sulfated sLex tetrasaccharides: 1a, 85%; 1b, 47%; 2a, 82%; 2b, 60%; 3a, 64%; 3b, 38%. Enzymes and abbreviations: NmCSS, Neisseria meningitidis CMP-sialic acid;37 PmST1 M144D, Pasteurella multocida α2-3-sialyltransferase 1 (PmST1) M144D mutant.40.
