L-ТРЕО-ПЕНТУЛОЗА

L-xylulose is a clear liquid. It is a ketopentose, meaning that it has five carbon atoms and a ketogroup at carbon C-2. It has a molecular formula of C5H10O5 and a molar mass of 150.13 g/mol. Xylulose is almost colorless and it forms syrup. The formation of crystals has not been reported (Budavari, 1996). Both D- and L - enantiomers of xylulose are found as intermediates in metabolic pathways of prokaryotes as well as eukaryotes. Both forms are rare in nature (Doten and Mortlock, 1985b).

L-Xylulose is used in studies relating to potential inhibitors of glycosidases and has been proven to inhibit oligosaccharide processing to a degree.

ChEBI: L-xylulose is a xylulose. It has a role as a human metabolite, an Escherichia coli metabolite and a mouse metabolite. It is an enantiomer of a D-xylulose.

L-Xylulose has been shown to be a specific inhibitor of certain α-glucosidases,while having virtually no effect on other glycosidases such as β-glucosidase or α- and β-mannosidases. Furthermore,it is a specific inhibitor of the N-linked glycoproteinprocessing enzyme，glucosidase I, but does not inhibit glucosidase I or otherglycoprotein processing mannosidases. Thus it could prove to be a useful inhibitor forstudying glycoprotein processing, especially as it has been proven to be non-toxic andto also be effective in cell cultures (Muniruzzaman et al., 1996). L-Xylulose has been shown to have a strong inhibitory effect on the a-glucosidases，sucrase and maltase, present in the small intestine. Thus, an L-xylulose containing drug preparation for reducing blood sugar levels in humans and animals has been patented (Heinz et al.,1998).

In 1933 a synthetic procedure for producing small amounts of D- and L -xylulose was introduced. In this method D- or L-xylose is epimerized to the corresponding diastereomer. The isomerization of xylose in pyridine leads to the production of xylulose (Touster, 1962). This enzyme catalyzes the production of L-xylulose from xylitol using either PQQ (pyrroloquinoline quinone) or FAD (flavin adenine dinucleotide) as prosthetic group, and L-xylulose is accumulated in the medium (Adachi et al., 1999; Adachi et al., 2001).