L-glucose
<p ><b><small>L</small>-Glucose</b> is an <a href="http://en.wikipedia.org/wiki/Organic_compound" title="Organic compound" >organic compound</a> with formula C<sub >6</sub>H<sub >12</sub>O<sub >6</sub> or H–(C=O)–(CHOH)<sub >5</sub>–H, specifically one of the <a href="http://en.wikipedia.org/wiki/Aldohexose" title="Aldohexose" >aldohexose</a><a href="http://en.wikipedia.org/wiki/Monosaccharide" title="Monosaccharide" >monosaccharides</a>. Its molecular structure is an <a href="http://en.wikipedia.org/wiki/Enantiomer" title="Enantiomer" >enantiomer</a> of the more common <a href="http://en.wikipedia.org/wiki/Glucose" title="Glucose" ><small>D</small>-glucose</a>.
<small>L</small>-Glucose does not occur naturally in higher living organisms, but can be <a href="http://en.wikipedia.org/wiki/Chemical_synthesis" title="Chemical synthesis" >synthesized</a> in the laboratory.</p>
<p>
<small>L</small>-Glucose is indistinguishable in taste from <small>D</small>-glucose,<sup id="cite_ref-levin_0-0" class="reference" ><a href="http://en.wikipedia.org/wiki/L-glucose#cite_note-levin-0" >[1]</a></sup> but cannot be used by living organisms as source of energy because it cannot be phosphorylated by <a href="http://en.wikipedia.org/wiki/Hexokinase" title="Hexokinase" >hexokinase</a>, the first enzyme in the <a href="http://en.wikipedia.org/wiki/Glycolysis" title="Glycolysis" >glycolysis</a> pathway. One of the known exceptions is in <i><a href="http://en.wikipedia.org/wiki/Burkholderia_caryophylli" title="Burkholderia caryophylli" >Burkholderia caryophylli</a></i>, the enzyme <small>D</small>-threo-aldolse dehydrogenase is capable of oxidising <small>L</small>-glucose<sup id="cite_ref-1" class="reference" ><a href="http://en.wikipedia.org/wiki/L-glucose#cite_note-1" >[2]</a></sup></p>
<p>
Like the '<small>D</small>-' isomer, <small>L</small>-glucose usually occurs as one of four cyclic structural <a href="http://en.wikipedia.org/wiki/Isomers" title="Isomers" class="mw-redirect" >isomers</a> — α- and β-<small>L</small>-glucopyranose (the most common, with a six-atom ring), and α- and β-<small>L</small>-glucofuranose (with a five-atom ring). In solution, these isomers interconvert in matters of hours, with the open-chain form as an intermediate stage.</p>
<h2 ></h2>
<h2 >Uses</h2>
<p ><small>L</small>-Glucose was once proposed as a low-calorie sweetener and it is suitable for patients of the diabetes mellitus, but was never marketed due to excessive manufacturing costs.<sup id="cite_ref-levin_0-1" class="reference" ><a href="http://en.wikipedia.org/wiki/L-glucose#cite_note-levin-0" >[1]</a></sup>
The <small>L</small>-glucose derivative, <a href="http://en.wikipedia.org/w/index.php?title=L-Glucose_pentaacetate&action=edit&redlink=1" class="new" title="L-Glucose pentaacetate (page does not exist)" ><small>L</small>-glucose pentaacetate</a>, was found to stimulate <a href="http://en.wikipedia.org/wiki/Insulin" title="Insulin" >insulin</a> release, and might therefore be of therapeutic value for <a href="http://en.wikipedia.org/wiki/Diabetes_mellitus_type_2" title="Diabetes mellitus type 2" >type 2 diabetes</a>.<sup id="cite_ref-2" class="reference" ><a href="http://en.wikipedia.org/wiki/L-glucose#cite_note-2" >[3]</a></sup> </p>
<p>
<small>L</small>-Glucose was also found to be a <a href="http://en.wikipedia.org/wiki/Laxative" title="Laxative" >laxative</a>, and proposed as a colon-cleansing agent which would not produce the disruption of fluid and electrolyte levels associated with the significant liquid quantities of bad-tasting osmotic <a href="http://en.wikipedia.org/wiki/Laxatives" title="Laxatives" class="mw-redirect" >laxatives</a>conventionally used in preparation for <a href="http://en.wikipedia.org/wiki/Colonoscopy" title="Colonoscopy" >colonoscopy</a>.<sup id="cite_ref-3" class="reference" ><a href="http://en.wikipedia.org/wiki/L-glucose#cite_note-3" >[4]</a></sup></p>