Lribulose

L-ribulose is the enantiomer of ribulose, a five-carbon ketose sugar. Like D-ribulose, it has the same molecular formula, C5H10O5, but its stereochemistry is the mirror image. In Fischer projection, the arrangement of the hydroxyl groups reflects the left-handed (L) configuration, and L-ribulose can also form cyclic forms such as L-ribofuranose in solution.

In biological systems, the D enantiomer of ribulose is the one encountered more commonly, notably as a precursor in the pentose phosphate pathway when it is phosphorylated to ribulose-5-phosphate. L-ribulose and its phosphate derivative are not widely documented as common intracellular metabolites in humans or other well-studied organisms. They may occur only in trace amounts or outside typical metabolic pathways, and their roles in biology, if any, are not well established. Some microorganisms may have enzymes with broader stereospecificity, but specific physiological functions for L-ribulose are not widely reported.

Synthesis and applications of L-ribulose are mainly in chemical and analytical contexts. It can be produced by chemical resolution of racemic ribulose or via asymmetric synthesis. In research settings, L-ribulose serves as a chiral reference compound or standard for calibrating instruments and studying stereospecific enzyme interactions with ketopentoses. Its chemical properties align with other ketopentoses: multiple hydroxyl groups, high water solubility, and reactivity at carbonyl and cyclic hemiacetal centers.