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6.3.1.2: glutamine synthetase

This is an abbreviated version!
For detailed information about glutamine synthetase, go to the full flat file.

Word Map on EC 6.3.1.2

Reaction

ATP
+
L-glutamate
 +
NH3
=
ADP
 +
phosphate
 +
L-glutamine

Synonyms

AmGLN1, ATP glutamate-ammonia ligase, Chloroplast GS2, Clone lambda-GS28, Clone lambda-GS31, Clone lambda-GS8, Cytoplasmic GS3, Cytosolic GS1, gamma-glutamyl transferase, gamma-glutamyl:ammonia ligase, gamma-glutamylhydroxamate synthetase, Gln isozyme alpha, Gln isozyme beta, Gln isozyme gamma, Gln synthetase, GLN1,1, GLN1,2, GLN1,3, GLN1,4, GLN1-1, GLN1-2, Gln1;1, Gln1;2, Gln1;3, Gln1;4, Gln1;5, GLN2, GlnA, glnA-1, GlnA1, GlnA2, GlnA3, GlnA4, GlnN, GlnR, GluA, GLUL, Glutamate--ammonia ligase, glutamate-ammonia ligase, Glutamine synthetase, glutamine synthetase cytosolic isozyme 1, glutamine synthetase cytosolic isozyme 2, glutamine synthetase I, glutamine synthetase type II, glutamine synthetase type III, Glutamylhydroxamic synthetase, GS, GS type I, GS type-1, GS(1), GS-II, GS1, GS1 kinase, GS1-1, GS1-2, GS107, GS112, GS117, GS12, GS122, GS1a, GS1beta1, GS1gamma1, GS2, GS2a, GS3, GSI, GSII, GSIII, Isozyme delta, L-glutamate:ammonia ligase, L-glutamate:ammonia ligase (ADP-forming), L-Glutamine synthetase, LDBPK_060370, LdGS, MM_0964, MtGS, N47/N48, OsGLN1,1, OsGLN1,2, protein transacetylase, S2205/S2287, SSO0366, Synthetase, glutamine, TAase, type I glutamine synthetase, type III glutamine synthetase

ECTree

     6 Ligases
         6.3 Forming carbon-nitrogen bonds
             6.3.1 Acid—ammonia (or amine) ligases (amide synthases)
                6.3.1.2 glutamine synthetase

General Stability

General Stability on EC 6.3.1.2 - glutamine synthetase

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GENERAL STABILITY
ORGANISM
UNIPROT
LITERATURE
activity is not reduced by digestion with trypsin or chymotrypsin at 37°C over 12 h
-
ATP decreases stability if present with lower concentrations of Mg2+ or Mn2+. When Mg2+ or Mn2+ is present in 4 mM excess over ATP, ATP slightly increases stability
-
below 2 M urea the enzyme retains its dodecameric structure and full catalytic activity. In 6 M urea, dissociation into subunits
-
EDTA and EGTA stabilize. The combination of substrates, Mn2+, ATP and PMSF
-
inactivation by trypsin, chymotrypsin, or subtilisin follows pseudo-fast order kinetics. In presence of Glu, ATP, and Mn2+ the digestion of the glutamine synthetase by each of the three proteases is retarded completely
-
isoform GS1 is more labile than isoform GS2 in the early stages of purification
-
keto compounds, e.g. 2-oxoglutarate, oxaloacetate or pyruvate, enhance stability during purification
-
mercaptoethanol and divalent metal ions are essential to maintain the enzyme activity
-
MgCl2, MgCl2 /Glu, or MgCl2/ATP are effective in stabilizing the enzyme. Glu or ATP also stabilize the enzyme but to a lesser extent. NH4Cl accelerates the enzyme inactivation, even in the presence of MgCl2
Mn2+ or Mg2+ required for stability, Mn2+ more effective than Mg2+
more than 50% loss of activity after one freeze/thaw cycle
-
myo-inositol (0.4 M) protects enzymatic activity during heat treatment, pinitol (0.4 M) results in maintenance of activity to 90% and 50% during heat treatment, glucose shows little tendency to protect the enzyme from loss of activity
-
native and oxidized forms of enzyme are both cleaved in the same manner by chymotrypsin. Oxidized enzyme is completely cleaved during the 60 min incubation whereas the native enzyme is not completely digested
-
native enzyme is more stable than metal ion-free enzyme
-
partially stabilized by divalent cation, Mg2+ or Mn2+, and by 0.5-1.5 M sucrose, 1-2.5 M fructose or 20-30% ethyleneglycol
-
purified enzyme being very unstable, is stabilized by 25% v/v glycerol
-
stability is enhanced by the presence of ethylene glycol
-
strongly stabilized in presence of Mn2+ but not with other divalent cations. Maximal stabilization at 1 mM
-
substrates, as L-Glu, Mg2+, and MgATP2- protect synthetase and glutamyl transferase activity against thermal inactivation
-
the presence of Mn2+ or Mg2+ drastically affects the thermostability of transferase activity and biosynthetic activity
-
thiol reagents are essential for stabilization of enzyme form GS2
-
with myo-inositol (0.4 M) 70.1% residual activity after 60°C heat treatment, with pinitol (0.4 M) 74.2% residual activity after 60°C heat treatment, with quercitol (0.4 M) 75.5% residual activity after 60°C heat treatment, with sorbitol (0.4 M) 62.0% residual activity after 60°C heat treatment, with proline (0.4 M) 72.2% residual activity after 60°C heat treatment, with glycinebetain (0.4 M) 67.7% residual activity after 60°C heat treatment, glucose shows little tendency to protect the enzyme from loss of activity
-