title: Regulation of glutaminase B in Escherichia coli. III. Control by nucleotides and divalent cations.
abstract: Glutaminase B from Escherichia coli is modulated by nucleotides and divalent cations. ATP and ADP inhibit glutaminase B whereas AMP and divalent cations activate it. Inhibition and activation required preincubation of the nucleotides with glutaminase B at 4 degrees. Mg2+, Mn2+, and Ca2+ activated the enzyme and prevented the inhibition by ATP. Dialysis in the presence of an activator ligand reversed the ATP inhibition of glutaminase B. The modulation of glutaminase B by energy charge is similar to that observed with other catabolic enzymes. We suggest that a pattern of reciprocal regulation of glutaminase B and glutamine synthetase by adenine nucleotides prevents the formation of a "futile cycle" of amide synthesis and degradation.
mesh_terms: D002118:Calcium / Q000494:pharmacology*; D004735:Energy Transfer; D004789:Enzyme Activation / Q000187:drug effects; D004926:Escherichia coli / Q000201:enzymology*; D005972:Glutaminase / Q000378:metabolism*; D007700:Kinetics; D008274:Magnesium / Q000494:pharmacology*; D008345:Manganese / Q000494:pharmacology*; D009994:Osmolar Concentration; D011189:Potassium Chloride / Q000494:pharmacology; D012265:Ribonucleotides / Q000494:pharmacology*; D012965:Sodium Chloride / Q000494:pharmacology; D013696:Temperature
chemical_list: D012265:Ribonucleotides; D008345:Manganese; D012965:Sodium Chloride; D011189:Potassium Chloride; D005972:Glutaminase; D008274:Magnesium; D002118:Calcium