title: Purification and properties of the arginine-specific carbamoyl-phosphate synthase from Saccharomyces cerevisiae.
abstract: The arginine-specific carbamoyl-phosphate synthase of yeast was stabilized sufficiently to allow partial purification of the enzyme (30- to 40-fold). The synthase (mol. wt 115000) comprised two unequal subunits: a heavy subunit (mol. wt 80000) capable of catalysing synthesis of carbamoyl phosphate with ammonia as a nitrogen donor and a light subunit conferring upon the holoenzyme the ability to utilize glutamine. The enzyme had unusually high affinity for ATP (Km = 0.2 mM) and atypical negative cooperativity for glutamine binding ([S]0.5 = 0.25 mM). Glutamine activity was not modulated by possible effectors such as arginine, ornithine or N-acetylglutamate. Thus, although the yeast arginine enzyme physically and functionally resembles the single enteric synthase, the systems differ substantially both in kinetic properties and in regulation of activity.
mesh_terms: D001120:Arginine / Q000096:biosynthesis*; D002222:Carbamoyl-Phosphate Synthase (Ammonia) / Q000302:isolation & purification* / Q000378:metabolism; D002223:Carbamoyl-Phosphate Synthase (Glutamine-Hydrolyzing) / Q000302:isolation & purification* / Q000378:metabolism; D046911:Macromolecular Substances; D010770:Phosphotransferases / Q000302:isolation & purification*; D012441:Saccharomyces cerevisiae / Q000201:enzymology*; D014158:Transcription, Genetic
chemical_list: D046911:Macromolecular Substances; D001120:Arginine; D010770:Phosphotransferases; D002222:Carbamoyl-Phosphate Synthase (Ammonia); D002223:Carbamoyl-Phosphate Synthase (Glutamine-Hydrolyzing)