Chemical modification of E. coli glutamine synthetase
Thiourea trioxide partially inactivates E. coli glutamine synthetase (GS) (approx.25%) by reacting only with lysine residues, producing homoarginine. Thiourea dioxide totally inactivates GS by reacting with both lysine and histidine residues. The K/sub m/ values for thiourea trioxide modified enzyme are 0.21 mM for ATP and 10 mM for glutamate which are about threefold higher than for native GS. Using (/sup 14/C) thiourea trioxide, 2.3 +/- 0.2 moles of reagent were incorporated per monomer. The same number of homoarginine residues were found by amino acid analysis. Modification of GS with hydroxylamine results in total inactivation resulting from reaction with histidine. Fluorescence titrations indicate that substrate binding to the modified enzyme is weaker than to the native enzyme. EPR spectra of bound Mn/sup 2 +/ indicate that metal ion binding is unaffected by hydroxylamine modification. However, metal ion binding is weaker to the modified enzyme. Protection from hydroxylamine inactivation is observed with ATP + Glutamate, AMPPNP + Glutamate, and MgCl/sub 2/.
- Research Organization:
- Pennsylvania State Univ., University Park
- OSTI ID:
- 5272738
- Report Number(s):
- CONF-8606151-; TRN: 86-031395
- Journal Information:
- Fed. Proc., Fed. Am. Soc. Exp. Biol.; (United States), Vol. 45:6; Conference: 76. annual meeting of the Federation of American Society for Experimental Biology, Washington, DC, USA, 8 Jun 1986
- Country of Publication:
- United States
- Language:
- English
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LIGASES
ENZYME ACTIVITY
THIOUREAS
BIOLOGICAL EFFECTS
ARGININE
ATP
BIOCHEMICAL REACTION KINETICS
CARBON 14 COMPOUNDS
ELECTRON SPIN RESONANCE
ESCHERICHIA COLI
FLUORESCENCE
GLUTAMIC ACID
HISTIDINE
LYSINE
MAGNESIUM CHLORIDES
SUBSTRATES
TRACER TECHNIQUES
ALKALINE EARTH METAL COMPOUNDS
AMINO ACIDS
AZOLES
BACTERIA
CARBONIC ACID DERIVATIVES
CARBOXYLIC ACIDS
CHLORIDES
CHLORINE COMPOUNDS
ENZYMES
HALIDES
HALOGEN COMPOUNDS
HETEROCYCLIC ACIDS
HETEROCYCLIC COMPOUNDS
IMIDAZOLES
ISOTOPE APPLICATIONS
KINETICS
LABELLED COMPOUNDS
LUMINESCENCE
MAGNESIUM COMPOUNDS
MAGNETIC RESONANCE
MICROORGANISMS
NUCLEOTIDES
ORGANIC ACIDS
ORGANIC COMPOUNDS
ORGANIC NITROGEN COMPOUNDS
ORGANIC SULFUR COMPOUNDS
REACTION KINETICS
RESONANCE
550201* - Biochemistry- Tracer Techniques