The kinetic mechanism of 5-enolpyruvylshikimate-3-phosphate synthase from a gram-positive pathogen Streptococcus pneumoniae.
J Enzyme Inhib
; 15(6): 571-81, 2000.
Article
em En
| MEDLINE
| ID: mdl-11140612
ABSTRACT
The Streptococcus pneumoniae 5-enolpyruvylshikimate-3-phosphate (EPSP) synthase is a potential novel antibacterial target. The enzyme catalyzes a reversible transfer of an enolpyruvyl group from phospho(enol)pyruvate (PEP) to shikimate 3-phosphate (S3P) to give EPSP with the release of inorganic phosphate (Pi). Understanding the kinetic mechanism of this enzyme is crucial to the design of novel inhibitors of this enzyme that may have potential as antibacterial agents. Steady-state kinetic studies of product inhibition and inhibition by glyphosate (GLP) have demonstrated diverse inhibition patterns of the enzyme. In the forward reaction, GLP is a competitive inhibitor with respect to PEP, but an uncompetitive inhibitor relative to S3P. Product inhibition shows that EPSP is a competitive inhibitor versus both PEP and S3P, suggesting that the forward reaction follows a random sequential mechanism. In the reverse reaction, GLP is an uncompetitive inhibitor versus EPSP, but a noncompetitive inhibitor versus Pi. This indicates that a non-productive quaternary complex might be formed between the enzyme, EPSP, GLP and Pi. Product inhibition in the reverse reaction has also been investigated. The inhibition patterns of the S. pneumoniae EPSP synthase are not entirely consistent with those of EPSP synthases from other species, indicating that EPSP synthases from different organisms may adopt unique mechanisms to catalyze the same reactions.
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Coleções:
01-internacional
Base de dados:
MEDLINE
Assunto principal:
Ácido Chiquímico
/
Streptococcus pneumoniae
/
Alquil e Aril Transferases
/
Glicina
Idioma:
En
Revista:
J Enzyme Inhib
Assunto da revista:
BIOQUIMICA
Ano de publicação:
2000
Tipo de documento:
Article
País de afiliação:
Estados Unidos