Identification of cysteine residues in carbamoyl-phosphate synthase I with reactivity enhanced by N-acetyl-L-glutamate.
Carbamoyl-phosphate synthase I (pig liver) is modified at the cysteine residues 1327 and 1337 (numbered according to the rat sequence) in the presence of 5 mM-N-acetyl-L-glutamate with enhanced rate. ATP/Mg2+ (greater than or equal to 5 mM) protects against alkylation of these two cysteines and loss of activity. According to the results obtained by limited proteolysis of monobromobimane-modified carbamoyl-phosphate synthase I, the accessible cysteines 1327 and 1337 are located in the C-terminal 20 kDa domain D of the enzyme. N-Bromoacetyl-L-glutamate is an allosteric activator and inactivates carbamoyl-phosphate synthase in a slow reaction.
Geschwill
K
K
Biochemisches Institut der Justus-Liebig-Universität Giessen, Federal Republic of Germany.
Lumper
L
L
D000255:Adenosine Triphosphate / Q000378:metabolism; D000595:Amino Acid Sequence; D000818:Animals; D019731:Carbon-Nitrogen Ligases; D003545:Cysteine / Q000302:isolation & purification*; D008025:Ligases / Q000302:isolation & purification*; D008969:Molecular Sequence Data; D013552:Swine
D000255:Adenosine Triphosphate; D008025:Ligases; D019731:Carbon-Nitrogen Ligases; C024233:carbamoyl-phosphate synthetase (N-acetylglutamate); D003545:Cysteine