Pyruvate-to-ethanol pathway in Entamoeba histolytica.
The pyruvate-to-ethanol pathway in Entamoeba histolytica is unusual when compared with most investigated organisms. Pyruvate decarboxylase (EC 4.1.1.1), a key enzyme for ethanol production, is not found. Pyruvate is converted into acetyl-CoA and CO2 by the enzyme pyruvate synthase (EC 1.2.7.1), which has been demonstrated previously in this parasitic amoeba. Acetyl-CoA is reduced to acetaldehyde and CoA by the enzyme aldehyde dehydrogenase (acylating) (EC 1.2.1.10) at an enzyme activity of 9 units per g of fresh cells with NADH as a reductant. Acetaldehyde is further reduced by either a previously identified NADP+-linked alcohol dehydrogenase or by a newly found NAD+-linked alcohol dehydrogenase at an enzyme activity of 136 units per g of fresh cells. Ethanol is identified as the product of soluble enzymes of amoeba acting on pyruvate or acetyl-CoA. This result is confirmed by radioactive isotopic, spectrophotometric and gas-chromatographic methods.
D000079:Acetaldehyde / Q000378:metabolism; D000105:Acetyl Coenzyme A / Q000378:metabolism; D055598:Chemical Phenomena; D002621:Chemistry; D004748:Entamoeba histolytica / Q000201:enzymology / Q000378:metabolism*; D000431:Ethanol / Q000378:metabolism*; D005486:Flavin Mononucleotide / Q000378:metabolism; D009243:NAD / Q000378:metabolism; D009249:NADP / Q000378:metabolism; D011773:Pyruvates / Q000378:metabolism*
D011773:Pyruvates; D009243:NAD; D000431:Ethanol; D009249:NADP; D000105:Acetyl Coenzyme A; D005486:Flavin Mononucleotide; D000079:Acetaldehyde