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2.3.3.1: citrate (Si)-synthase

This is an abbreviated version!
For detailed information about citrate (Si)-synthase, go to the full flat file.

Word Map on EC 2.3.3.1

Reaction

acetyl-CoA
+
H2O
 +
oxaloacetate
=
citrate
 +
CoA

Synonyms

(R)-citric synthase, citrate oxaloacetate-lyase ((pro-3S)-CH2COO---> acetyl-CoA), citrate synthase, citrate synthase isoform a, citrate synthase isoform b, CLO1313_RS02945, CS, EC 4.1.3.7, HCS

ECTree

     2 Transferases
         2.3 Acyltransferases
             2.3.3 Acyl groups converted into alkyl groups on transfer
                2.3.3.1 citrate (Si)-synthase

Temperature Stability

Temperature Stability on EC 2.3.3.1 - citrate (Si)-synthase

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TEMPERATURE STABILITY
ORGANISM
UNIPROT
COMMENTARY hide
LITERATURE
0
sequences and structures of citrate synthases from the psychrophile antarctic bacterium DS2-3R, from chicken, and from the hyperthermophile Pyrococcus furiosus are compared. The three enzymes share similar packing, burial of nonpolar surface area, and main-chain hydrogen bonding. However, both psychrophilic and hyperthermophilic citrate synthases contain more charged residues, salt bridges, and salt-bridge networks than the mesophile. The electrostatic free energy contributions toward protein stability by individual charged residues show greater variabilities in the psychrophilic citrate synthase than in the hyperthermophilic enzyme. The charged residues in the active-site regions of the psychrophile are more destabilizing than those in the active-site regions of the hyperthermophile.In the hyperthermophilic enzyme, salt bridges and their networks largely cluster in the active-site regions and at the dimer interface. In contrast, in the psychrophile, they are more dispersed throughout the structure. On average, salt bridges and their networks provide greater electrostatic stabilization to the thermophilic citrate synthase at 100°C than to the psychrophilic enzyme at 0°C. Electrostatics appears to play an important role in both heat and cold adaptation of citrate synthase. However, remarkably, the role may be different in the two types of enzyme: In the hyperthermophile, it may contribute to the integrity of both the protein dimer and the active site by possibly countering conformational disorder at high temperatures. On the other hand, in the psychrophile at low temperatures, electrostatics may contribute to enhance protein solvation and to ensure active-site flexibility
100
sequences and structures of citrate synthases from the psychrophile Arthobacter Ds2-3R, from chicken, and from the hyperthermophile Pyrococcus furiosus are compared. The three enzymes share similar packing, burial of nonpolar surface area, and main-chain hydrogen bonding. However, both psychrophilic and hyperthermophilic citrate synthases contain more charged residues, salt bridges, and salt-bridge networks than the mesophile. The electrostatic free energy contributions toward protein stability by individual charged residues show greater variabilities in the psychrophilic citrate synthase than in the hyperthermophilic enzyme. The charged residues in the active-site regions of the psychrophile are more destabilizing than those in the active-site regions of the hyperthermophile.In the hyperthermophilic enzyme, salt bridges and their networks largely cluster in the active-site regions and at the dimer interface. In contrast, in the psychrophile, they are more dispersed throughout the structure. On average, salt bridges and their networks provide greater electrostatic stabilization to the thermophilic citrate synthase at 100°C than to the psychrophilic enzyme at 0°C. Electrostatics appears to play an important role in both heat and cold adaptation of citrate synthase. However, remarkably, the role may be different in the two types of enzyme: In the hyperthermophile, it may contribute to the integrity of both the protein dimer and the active site by possibly countering conformational disorder at high temperatures. On the other hand, in the psychrophile at low temperatures, electrostatics may contribute to enhance protein solvation and to ensure active-site flexibility
38
-
thermal inactivation: less than 12% of activity remains after 60 min
additional information