d-pantolactone is an intermediate in the synthesis of
d-pantothenic acid, which is known as vitamin B
5. The commercial synthesis of
d-pantolactone is carried out through the selective resolution of
dl-pantolactone catalyzed by lactone hydrolase. In contrast to
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d-pantolactone is an intermediate in the synthesis of
d-pantothenic acid, which is known as vitamin B
5. The commercial synthesis of
d-pantolactone is carried out through the selective resolution of
dl-pantolactone catalyzed by lactone hydrolase. In contrast to a kinetic resolution approach, the deracemization of
dl-pantolactone is a simpler, greener, and more sustainable way to obtain
d-pantolactone with high optical purity. Herein, an efficient three-enzyme cascade was developed for the deracemization of
dl-pantolactone, using
l-pantolactone dehydrogenase from
Amycolatopsis methanolica (
AmeLPLDH), conjugated polyketone reductase from
Zygosaccharomyces parabailii (
ZpaCPR), and glucose dehydrogenase from
Bacillus subtilis (
BsGDH). The
AmeLPLDH was used to catalyze the dehydrogenated
l-pantolactone into ketopantolactone; the
ZpaCPR was used to further catalyze the ketopantolactone into
d-pantolactone; and glucose dehydrogenase together with glucose fulfilled the function of coenzyme regeneration. All three enzymes were co-expressed in
E. coli strain BL21(DE3), which served as the whole-cell biocatalyst. Under optimized conditions, 36 h deracemization of 1.25 M
dl-pantolactone
d-pantolactone led to an
e.e.p value of 98.6%, corresponding to productivity of 107.7 g/(l·d).
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