Gene/Protein
Disease
Symptom
Drug
Enzyme
Compound
Pivot Concepts:
Gene/Protein
Disease
Symptom
Drug
Enzyme
Compound
Target Concepts:
Gene/Protein
Disease
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Enzyme
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Query: UNIPROT:P00790 (
PGA
)
2,475
document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)
The mechanism of catalysis by the L-glutaminase-asparaginase from Pseudomonas 7A (
PGA
) was investigated using structural, mass spectrometry, and kinetic data. We had previously proposed mechanism of hydrolysis of L-Asn by the type II
L-asparaginase
from E. coli (EcAII), but that work was limited to just one enzyme. Based on results presented in this report, we postulate that all homotetrameric L-asparaginases from mesophilic bacteria utilize a common ping-pong mechanism of catalysis consisting of two subsequent nucleophilic substitutions. Several new structures of non-covalent complexes of
PGA
with different substrates, as well as structures of covalent acyl-enzyme intermediates of
PGA
with canonical substrates (L-Asp and L-Glu) and an opportunistic ligand, a citrate anion, were determined. The results of kinetic experiments monitored by high-resolution LC/MS, when combined with new structural data, clearly show that the reaction catalyzed by L-glutaminase-asparaginases proceeds through formation of a covalent intermediate, as observed previously for EcAII. Additionally, by showing that the same mechanism applies to L-Asn and L-Gln, we postulate that it is common for all these structurally related enzymes.
...
PMID:Generalized enzymatic mechanism of catalysis by tetrameric L-asparaginases from mesophilic bacteria. 3306 Jun 84
