Glutamine
<p><b >Glutamine</b> (abbreviated as <b >Gln</b> or <b >Q</b>) is one of the 20 <a href="http://en.wikipedia.org/wiki/Amino_acid" title="Amino acid" >amino acids</a> encoded by the standard <a href="http://en.wikipedia.org/wiki/Genetic_code" title="Genetic code" >genetic code</a>. It is not recognized as an <a href="http://en.wikipedia.org/wiki/Essential_amino_acid" title="Essential amino acid" >essential amino acid</a> but may become conditionally essential in certain situations, including intensive athletic training or certain gastrointestinal disorders.<sup class="Template-Fact" >[<i><a href="http://en.wikipedia.org/wiki/Wikipedia:Citation_needed" title="Wikipedia:Citation needed" >citation needed</a></i>]</sup> Its <a href="http://en.wikipedia.org/wiki/Side-chain" title="Side-chain" class="mw-redirect" >side-chain</a> is an <a href="http://en.wikipedia.org/wiki/Amide" title="Amide" >amide</a> formed by replacing the side-chain <a href="http://en.wikipedia.org/wiki/Hydroxyl" title="Hydroxyl" >hydroxyl</a> of <a href="http://en.wikipedia.org/wiki/Glutamic_acid" title="Glutamic acid" >glutamic acid</a> with an<a href="http://en.wikipedia.org/wiki/Amine" title="Amine" >amine</a> <a href="http://en.wikipedia.org/wiki/Functional_group" title="Functional group" >functional group</a> making it the amide of <a href="http://en.wikipedia.org/wiki/Glutamic_acid" title="Glutamic acid" >glutamic acid</a>. Its <a href="http://en.wikipedia.org/wiki/Genetic_code" title="Genetic code" >codons</a> are CAA and CAG. In human blood, glutamine is the most abundant free <a href="http://en.wikipedia.org/wiki/Amino_acid" title="Amino acid" >amino acid</a>, with a concentration of about 500-900 µmol/L.<sup id="cite_ref-Brosnan_1-0" class="reference" ><a href="http://en.wikipedia.org/wiki/Glutamine#cite_note-Brosnan-1" >[2]</a></sup>
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<h2 >Functions</h2>
<p >Glutamine plays a role in a variety of biochemical functions including:</p>
<ul >
<li >Protein synthesis, as any other <a href="http://en.wikipedia.org/wiki/Amino_acid" title="Amino acid" >amino acid</a>.</li>
<li >Regulation of acid-base balance in the kidney by producing <a href="http://en.wikipedia.org/wiki/Ammonium" title="Ammonium" >ammonium</a>.<sup id="cite_ref-2" class="reference" ><a href="http://en.wikipedia.org/wiki/Glutamine#cite_note-2" >[3]</a></sup></li>
<li >Cellular energy, as a source, next to <a href="http://en.wikipedia.org/wiki/Glucose" title="Glucose" >glucose</a>.<sup id="cite_ref-3" class="reference" ><a href="http://en.wikipedia.org/wiki/Glutamine#cite_note-3" >[4]</a></sup></li>
<li ><a href="http://en.wikipedia.org/wiki/Nitrogen" title="Nitrogen" >Nitrogen</a> donation for many <a href="http://en.wikipedia.org/wiki/Anabolism" title="Anabolism" >anabolic processes</a> including the synthesis of <a href="http://en.wikipedia.org/wiki/Purine_metabolism" title="Purine metabolism" >purines</a>.<sup id="cite_ref-Brosnan_1-1" class="reference" ><a href="http://en.wikipedia.org/wiki/Glutamine#cite_note-Brosnan-1" >[2]</a></sup></li>
<li >Carbon donation, as a source, refilling the <a href="http://en.wikipedia.org/wiki/Citric_acid_cycle" title="Citric acid cycle" >citric acid cycle</a>.<sup id="cite_ref-Yuneva_4-0" class="reference" ><a href="http://en.wikipedia.org/wiki/Glutamine#cite_note-Yuneva-4" >[5]</a></sup></li>
<li >Nontoxic transporter of ammonia in the blood circulation.</li>
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<p> </p>
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In catabolic states of injury and illness, glutamine becomes conditionally-essential (requiring intake from food or supplements).<sup class="Template-Fact" >[<i><a href="http://en.wikipedia.org/wiki/Wikipedia:Citation_needed" title="Wikipedia:Citation needed" >citation needed</a></i>]</sup> Glutamine has been studied extensively over the past 10–15 years and has been shown to be useful in treatment of injuries, trauma, burns, and treatment-related side-effects of cancer as well as in wound healing for postoperative patients.<sup id="cite_ref-umm.edu_7-0" class="reference" ><a href="http://en.wikipedia.org/wiki/Glutamine#cite_note-umm.edu-7" >[8]</a></sup> Glutamine is also marketed as a supplement used for muscle growth in <a href="http://en.wikipedia.org/wiki/Powerlifting" title="Powerlifting" >weightlifting</a>, <a href="http://en.wikipedia.org/wiki/Bodybuilding" title="Bodybuilding" >bodybuilding</a>, <a href="http://en.wikipedia.org/wiki/Outline_of_sports#Endurance_sports" title="Outline of sports" >endurance</a>, and other sports. Evidence indicates that glutamine when orally loaded may increase plasma <a href="http://en.wikipedia.org/wiki/HGH" title="HGH" class="mw-redirect" >HGH</a> levels by stimulating the anterior pituitary gland.<sup id="cite_ref-8" class="reference" ><a href="http://en.wikipedia.org/wiki/Glutamine#cite_note-8" >[9]</a></sup> In biological research, L-glutamine is commonly added<sup id="cite_ref-9" class="reference" ><a href="http://en.wikipedia.org/wiki/Glutamine#cite_note-9" >[10]</a></sup> to the media in <a href="http://en.wikipedia.org/wiki/Cell_culture" title="Cell culture" >cell culture</a>.
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<h3 >Occurrences in nature</h3>
<p >Glutamine is the most abundant naturally occurring, non-<a href="http://en.wikipedia.org/wiki/Essential_amino_acid" title="Essential amino acid" >essential amino acid</a> in the human body and one of the few amino acids that can directly cross the <a href="http://en.wikipedia.org/wiki/Blood%E2%80%93brain_barrier" title="Blood–brain barrier" >blood–brain barrier</a>.<sup id="cite_ref-11" class="reference" ><a href="http://en.wikipedia.org/wiki/Glutamine#cite_note-11" >[12]</a></sup>In the body, it is found circulating in the blood as well as stored in the <a href="http://en.wikipedia.org/wiki/Skeletal_muscle" title="Skeletal muscle" class="mw-redirect" >skeletal muscles</a>. It becomes conditionally essential (requiring intake from food or supplements) in states of illness or injury.<sup id="cite_ref-umm.edu_7-1" class="reference" ><a href="http://en.wikipedia.org/wiki/Glutamine#cite_note-umm.edu-7" >[8]</a></sup></p>
<h4 >Dietary sources</h4>
<p >Dietary sources of <small>L</small>-glutamine include beef, chicken, fish, eggs, milk, dairy products, wheat, cabbage, beets, beans,
spinach, and <a href="http://en.wikipedia.org/wiki/Parsley" title="Parsley" >parsley</a>. Small amounts of free <small>L</small>-glutamine are also found in vegetable juices.<sup id="cite_ref-12" class="reference" ><a href="http://en.wikipedia.org/wiki/Glutamine#cite_note-12" >[13]</a></sup><sup class="noprint Inline-Template" >[<i><a href="http://en.wikipedia.org/wiki/Wikipedia:Identifying_reliable_sources" title="Wikipedia:Identifying reliable sources" >unreliable source?</a></i>]</sup></p>
<p>
In recent studies, glutamine-enriched diets have been linked with intestinal effects including maintenance of <a href="http://en.wikipedia.org/wiki/Enterocyte" title="Enterocyte" >gut barrier</a> function and cell differentiation. This may relate to the fact that the intestinal extraction rate of glutamine is higher than that for other amino acids, and is therefore thought to be the most viable option when attempting to alleviate conditions relating to the gastrointestinal tract. These conditions were discovered within the gut between glutamine-enriched and non-glutamine-enriched diets. However, even though glutamine is thought to have "cleansing" properties and effects, it is unknown to what extent glutamine has clinical benefits, due to the varied concentrations of glutamine in varieties of food.<sup id="cite_ref-13" class="reference" ><a href="http://en.wikipedia.org/wiki/Glutamine#cite_note-13" >[14]</a></sup> </p>
<p>
Glutamine may help to protect the lining of the gastrointestinal tract or mucosa. It has been suggested that people who have inflammatory bowel disease IBD (ulcerative colitis and Crohn' s disease) may not have enough glutamine. However, two clinical trials found that taking glutamine supplements did not improve symptoms of Crohn' s disease.</p>