S. Blayer et al., Alkaline biocatalysis for the direct synthesis of N-acetyl-D-neuraminic acid (Neu5Ac) from N-acetyl-D-glucosamine (GlcNAc), BIOTECH BIO, 66(2), 1999, pp. 131-136
Integration between the alkaline epimerization of N-acetyl-D-glucosamine (G
lcNAc) to N-Acetyl-D-mannosamine (ManNAc) and the N-acetyl-D-neuraminic aci
d (Neu5Ac) aldolase-catalyzed biotransformation has been assessed experimen
tally. GlcNAc epimerization took place above pH 9.0, and the initial rate o
f ManNAc formation increased exponentially to 10.37 mmol/L per hour at pH 1
2. However, above this pH, severe degradation of pyruvate occurred. A value
of 31.3% molar conversion on Pyr was achieved in an integrated biotransfor
mation. The "pseudo"-steady state at the end of the reaction was comparable
to the equilibrium achieved with a combination of an epimerase and aldolas
e enzymes. The integrated reaction proved feasible, but at the expense of p
yruvate and Neu5Ac aldolase degradation. (C) 1999 John Wiley & Sons, Inc.