title: Mechanism of L-serine oxidation in Entamoeba histolytica.
abstract: 1. The enzymatic mechanism of oxygen uptake elicited by L-serine in axenically cultivated trophozoites of Entamoeba histolytica was investigated. 2. Of 22 amino acids examined, only L-serine stimulated oxygen consumption by intact and disrupted amoebae. 3. Pyruvate, a product of serine metabolism, also stimulated oxygen consumption in the amoebae. 4. Characterization of the oxygen uptake elicited by both L-serine and pyruvate, and analysis of the products of L-serine metabolism indicate that the amino acid is first converted to pyruvate. 5. L-Serine dehydratase, which catalyzes the deamination of serine to pyruvate, was detected primarily in the soluble fraction of the amoebae. D-Serine potently inhibited the enzyme, as well as oxygen uptake in the presence of L-serine but not in the presence of pyruvate. 6. The pyruvate formed is oxidized, at least in part, by a novel pyruvate oxidase involving the uptake of molecular oxygen.
mesh_terms: D000105:Acetyl Coenzyme A / Q000378:metabolism; D000641:Ammonia / Q000378:metabolism; D000818:Animals; D004748:Entamoeba histolytica / Q000187:drug effects / Q000378:metabolism*; D012695:L-Serine Dehydratase / Q000378:metabolism; D010084:Oxidation-Reduction; D010101:Oxygen Consumption / Q000187:drug effects; D011771:Pyruvate Oxidase / Q000378:metabolism; D011773:Pyruvates / Q000378:metabolism / Q000494:pharmacology; D019289:Pyruvic Acid; D012694:Serine / Q000378:metabolism* / Q000494:pharmacology
chemical_list: D011773:Pyruvates; D012694:Serine; D000105:Acetyl Coenzyme A; D000641:Ammonia; D019289:Pyruvic Acid; D011771:Pyruvate Oxidase; D012695:L-Serine Dehydratase