Editing Glycerol (section)

==Metabolism==
Glycerol is a precursor for synthesis of [[triacylglycerol]]s and of [[phospholipid]]s in the liver and [[adipose tissue]]. When the body uses stored fat as a source of energy, glycerol and [[fatty acid]]s are released into the bloodstream.

Glycerol is mainly metabolized in the liver. Glycerol injections can be used as a simple test for liver damage, as its rate of absorption by the liver is considered an accurate measure of liver health. Glycerol metabolism is reduced in both cirrhosis and [[fatty liver disease]].<ref>Glycerol clearance in alcoholic liver disease. Gut (British Society of Gastroenterology). 1982 Apr; 23(4): 257–264. D G Johnston, K G Alberti, R Wright, P G Blain</ref><ref>"Fatty liver disrupts glycerol metabolism in gluconeogenic and lipogenic pathways in humans". September 2018 ''The Journal of Lipid Research'', 59, 1685–1694. Jeffrey D. Browning, Eunsook S. Jin1, Rebecca E. Murphy, and Craig R. Malloy</ref>

Blood glycerol levels are highly elevated during [[diabetes]], and is believed to be the cause of reduced fertility in patients who suffer from diabetes and metabolic syndrome. Blood glycerol levels in diabetic patients average three times higher than healthy controls. Direct glycerol treatment of testes has been found to cause significant long-term reduction in sperm count. Further testing on this subject was abandoned due to the unexpected results, as this was not the goal of the experiment.<ref>''Molecular Human Reproduction'', Volume 23, Issue 11, November 2017, pp. 725–737</ref>

Circulating glycerol does not [[glycate]] proteins as do [[glucose]] or fructose, and does not lead to the formation of [[advanced glycation endproduct]]s (AGEs). In some organisms, the glycerol component can enter the [[glycolysis]] pathway directly and, thus, provide energy for cellular metabolism (or, potentially, be converted to glucose through [[gluconeogenesis]]).

Before glycerol can enter the pathway of glycolysis or gluconeogenesis (depending on physiological conditions), it must be converted to their intermediate [[glyceraldehyde 3-phosphate]] in the following steps:
<div class="toccolours" style="font-size:90%; margin:auto; display: flex; overflow-x: auto">
{{Biochem reaction subunit|compound=Glycerol|class=skin-invert-image|image=Glycerin Skelett.svg|image_size=100}}
{{Biochem reaction subunit|enzyme=Glycerol kinase|for_subst=ATP|for_prod=ADP}}
{{Biochem reaction subunit|compound=Glycerol-3-phosphate|class=skin-invert-image|image=Glycerol-3-phosphate.png|image_size=100}}
{{Biochem reaction subunit|enzyme=Glycerol-3-phosphate dehydrogenase|direction=reversible|for_subst=NAD<sup>+</sup>|for_prod=NADH|rev_prod=NAD<sup>+</sup>|rev_subst=NADH}}
{{Biochem reaction subunit|compound=Dihydroxyacetone phosphate|class=skin-invert-image|image=DHAP struct.svg|image_size=125}}
{{Biochem reaction subunit|enzyme=Triosephosphate isomerase|direction=reversible}}
{{Biochem reaction subunit|compound=Glyceraldehyde 3-phosphate|class=skin-invert-image|image=D-Glycerinaldehyde 3-phosphate Structural Formula V1.svg|image_size=150px}}
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The enzyme [[glycerol kinase]] is present mainly in the liver and kidneys, but also in other body tissues, including muscle and brain.<ref>{{cite journal |pmc=1163884|pmid=183753|year=1976|last1=Tildon|first1=J. T.|title=Mitochondrial glycerol kinase activity in rat brain|journal=The Biochemical Journal|volume=157|issue=2|pages=513–516|last2=Stevenson|first2=J. H. Jr.|last3=Ozand|first3=P. T.|doi=10.1042/bj1570513}}</ref><ref>{{cite journal |title=Glycerol kinase activities in muscles from vertebrates and invertebrates|pmid=5801671 |pmc= 1187734 |volume=112|issue=4|date=May 1969|journal=Biochem. J.|pages=465–474|last1=Newsholme|first1=E. A.|last2=Taylor|first2=K|doi=10.1042/bj1120465}}</ref><ref>{{cite journal |vauthors= Jenkins, BT, Hajra, AK |date= 1976 |title= Glycerol Kinase and Dihydroxyacetone Kinase in Rat Brain |journal= Journal of Neurochemistry |volume= 26 |issue= 2 |pages= 377–385 |doi= 10.1111/j.1471-4159.1976.tb04491.x |pmid= 3631 |hdl= 2027.42/65297 |s2cid= 14965948 |url= https://deepblue.lib.umich.edu/bitstream/2027.42/65297/1/j.1471-4159.1976.tb04491.x.pdf |hdl-access= free |access-date= 27 August 2019 |archive-date= 21 February 2022 |archive-url= https://web.archive.org/web/20220221143240/https://deepblue.lib.umich.edu/bitstream/handle/2027.42/65297/j.1471-4159.1976.tb04491.x.pdf;jsessionid=27E5DB761F19C9F26C4F8EF4EDC33819?sequence=1 |url-status= live }}</ref> In adipose tissue, glycerol 3-phosphate is obtained from [[dihydroxyacetone phosphate]] with the enzyme [[glycerol-3-phosphate dehydrogenase]].