Biosynthesis of rare hexoses using microorganisms and related enzymes

Abstract

SummaryRare sugars, referred to as monosaccharides and their derivatives that rarely exist in nature, can be applied in many areas ranging from foodstuffs to pharmaceutical and nutrition industry, or as starting materials for various natural products and drug candidates. Unfortunately, an important factor restricting the utilization of rare sugars is their limited availability, resulting from limited synthetic methods. Nowadays, microbial and enzymatic transformations have become a very powerful tool in this field. This article reviews the biosynthesis and enzymatic production of rare ketohexoses, aldohexoses and sugar alcohols (hexitols), including D-tagatose, D-psicose, D-sorbose, L-tagatose, L-fructose, 1-deoxy-L-fructose, D-allose, L-glucose, L-talose, D-gulose, L-galactose, L-fucose, allitol, D-talitol, and L-sorbitol. New systems and robust catalysts resulting from advancements in genomics and bioengineering are also discussed.

Characterization of a d-psicose 3-epimerase from Dorea sp. CAG317 with an acidic pH optimum and a high specific activity

“…Rare sugars, which are defined by the International Society of Rare Sugars (ISIR) as the monosaccharides and their derivatives rarely existing in nature, are attracting increasing attention of researchers, due to their great potential in food, medical, and chemical fields [1,2]. Based on decades of scientific efforts, the research groups (especially Ken Izumori group) in the Kagawa University Rare Sugar Research Center have created a cyclic bioconversion strategy, named Izumoring, by which all monosaccharides become interrelated by means of several groups of biocatalysts [3][4][5].…”

Influence of Low Glycaemic Index Sweeteners on Antioxidant, Sensory, Mechanical, and Physicochemical Properties of a Watermelon Jelly

“…The unabsorbed tagatose is fermented in the colon, where it acts as soluble fibre [15,16]. Besides, it does not promote tooth decay and it only provides 1.5 kcal/g to diet [17]. Tagatose was generally recognized as safe (GRAS) in 2010 [18].…”

Enzymatic synthesis of rare sugars with l-rhamnulose-1-phosphate aldolase from Thermotoga maritima MSB8

“…Contrastingly and as achieved in our previous study and literature, L-fructose was exclusively produced when RhaD E. coli accepts L-glyceraldehyde as the acceptor. [3][4][5] Since RhaD T.mari is from a thermophilic source, we are curious to know the temperature effect on its activity. Thus, aldol reactions catalyzed by RhaD T.mari without Nus tag using DHAP and D-glyceraldehyde as substrates were carried out at a 8 series of temperature.…”

“…Recent progress of the biosynthesis of rare hexoses including ketohexoses, aldohexoses, and sugar alcohols was summarized in our recent review. 4 Our group has been focusing on the in vitro enzymatic synthesis of rare sugars and we mainly used DHAP-dependent aldolases because they have been proven remarkably useful due to their predictable stereochemical outcome and thus widely investigated among the aldolase families. [5][6][7] For example, L-rhamnulose-1-phosphate aldolase (RhaD) is a commonly used enzyme that catalyzes the reversible cleavage of L-rhamnulose-1-phosphate to dihydroxyacetone phosphate (DHAP) and L-lactaldehyde (Scheme 1).…”