L-sugars and their derivatives hold great promise for application in both the pharmaceutical and
food industry. Enzymatic approaches to produce these rare sugars offer a green and economic
alternative to the conventional chemical processes. Accordingly, a biocatalytic production process
will be developed by combining enzyme engineering and pathway design. In particular, C5-
epimerases will be our enzymes of choice since they are able to directly interconvert D- and Lhexoses,
thereby generating a bridge between the abundant D-sugars and their scarce Lcounterparts.
However, only a couple of such C5-epimerases are known to exist in nature,
meaning that enzyme engineering will be needed to create new and industrially relevant
specificities. A prime example is the conversion of UDP-D-glucose to UDP-L-talose, which can be
applied in the synthesis of antibiotic and anti-cancer drugs. To keep the cost of the final product as
low as possible, sucrose synthase will be incorporated into the process since this enzyme is able to
synthesize UDP-D-glucose from sucrose as abundant and cheap substrate. In the end, a complete
pathway will be assembled and optimized for the one-pot synthesis of L-sugars from sucrose, by
combining sucrose synthase, the engineered epimerases and additional enzymes. By simply
changing the epimerase specificity, virtually any L-sugar and derivative should be within our reach,
hereby highlighting the generic character of our strategy/platform technology.