Independent bindings of Mn2+ and Mg2+ to the active site of B. cereus glutamine synthetase.
Glutamine synthetase purified from Bacillus cereus IFO 3131 was modified by iodoacetamide and the ATP analog 5'-p-fluorosulfonylbenzoyladenosine (FSBA). Only Mg2+-dependent activity was inactivated by iodoacetamide, whereas only Mn2+-dependent activity was inactivated by FSBA. When iodoacetamide-treated enzyme was reacted with FSBA, Mn2+-dependent activity was also inactivated. Mg2+ plus Mn2+-dependent activity was inactivated in any case. The results suggested that the binding sites of Mn2+ and Mg2+ are separate from each other in the active site of B. cereus glutamine synthetase and that bindings of Mg2+ and Mn2+ to each site are required for normal activity in vivo.
D000241:Adenosine / Q000031:analogs & derivatives / Q000494:pharmacology; D000255:Adenosine Triphosphate / Q000494:pharmacology; D001409:Bacillus cereus / Q000201:enzymology*; D001665:Binding Sites; D005974:Glutamate-Ammonia Ligase / Q000032:analysis / Q000378:metabolism*; D005971:Glutamates / Q000494:pharmacology; D018698:Glutamic Acid; D007460:Iodoacetamide / Q000494:pharmacology; D007700:Kinetics; D008274:Magnesium / Q000378:metabolism*; D008345:Manganese / Q000378:metabolism*; D013438:Sulfhydryl Compounds / Q000032:analysis
D005971:Glutamates; D013438:Sulfhydryl Compounds; D018698:Glutamic Acid; D008345:Manganese; C010959:5'-(4-fluorosulfonylbenzoyl)adenosine; D000255:Adenosine Triphosphate; D005974:Glutamate-Ammonia Ligase; D008274:Magnesium; D000241:Adenosine; D007460:Iodoacetamide