title: A multienzyme complex for CO2 fixation.
abstract: Acetyl-coenzyme A carboxylase from Euglena gracilis strain Z was isolated as a component of a multienzyme complex which includes phosphoenolpyruvate carboxylase and malate dehydrogenase. The multienzyme complex was shown to exist in crude extracts and was purified to a homogeneous protein with a molecular weight of 360,000 by gel filtration. The ratio of the activities of the constituent enzymes was acetyl-CoA carboxylase:phosphoenolpyruvate carboxylase:malate dehydrogenase, 1:25:500. The complex is proposed to operate in conjunction with malic enzyme, which is present in Euglena, to facilitate the formation of substrates, malonyl-CoA, and NADPH, for fatty acid biosynthesis. The interaction of the enzymes may represent a means of control of acetyl-CoA carboxylase activity in organisms which do not possess an enzyme subject to allosteric regulation. The acetyl-CoA carboxylase activity from Euglena is unaffected by citrate and isocitrate.
mesh_terms: D000103:Acetyl-CoA Carboxylase / Q000302:isolation & purification* / Q000378:metabolism; D000818:Animals; D002245:Carbon Dioxide / Q000378:metabolism*; D005056:Euglena gracilis / Q000201:enzymology* / Q000378:metabolism; D005227:Fatty Acids / Q000096:biosynthesis; D008025:Ligases / Q000302:isolation & purification*; D008291:Malate Dehydrogenase / Q000302:isolation & purification* / Q000378:metabolism; D008970:Molecular Weight; D009097:Multienzyme Complexes / Q000302:isolation & purification*; D010729:Phosphoenolpyruvate Carboxykinase (GTP) / Q000302:isolation & purification* / Q000378:metabolism
chemical_list: D005227:Fatty Acids; D009097:Multienzyme Complexes; D002245:Carbon Dioxide; D008291:Malate Dehydrogenase; D010729:Phosphoenolpyruvate Carboxykinase (GTP); D008025:Ligases; D000103:Acetyl-CoA Carboxylase