What is the difference between L-arabinose and D-arabinose?

L-arabinose and D-arabinose are isomers
L-Arabinose is an arabinose isomer widely found in nature, while D-arabinose is less common. L-Arabinose is usually a constituent of several biopolymers that make upwards plant cell walls. This particular monosaccharide is normally employed in mobile culture media, serving as a bacterial carbon supply, and may be used to distinguish between bacteria based about their fermentation abilities. L-Arabinose, in the a shortage of blood sugar, induces transcription in the perruche operon in E. coli that encodes L-arabinose catabolizing enzymes. It does this by binding to the AraC protein and initiating the PBAD promoter. The PBAD promoter is employed inside plasmid vectors as a new switch for protein expression that can be started up by L-arabinose or switched off by addition of glucose.

You can find 8 stereoisomers of arabinose, commonly known as β-L-arabinose and β-D-arabinose. Natural L-arabinose is widely found within foods, usually along with other monosaccharides, in the form of heteropolysaccharides. It is identified in colloids, hemicelluloses, pectic acids, bacterial polysaccharides plus certain glycosides. D-arabinose is normally obtained by artificial activity and is rare within nature, occasionally inside the tissue of certain E. coli or Mycobacterium tuberculosis.