Inhibition of human placenta glutathione transferase P1-1 by the antibiotic calvatic acid and its diazocyanide analogue evidence for multiple catalytic intermediates

Giovanni Antonini, Giuseppina Pitari, Anna Maria Caccuri, Giorgio Ricci, Donatella Boschi, Roberta Fruttero, Alberto Gasco, Paolo Ascenzi

Research output: Contribution to journalArticle

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Abstract

The inhibition mechanism of the dimeric human placenta glutathione transferase (GST) P1-1 by calvatic acid and the reaction intermediates, i.e. the diazocyanide analogue of calvatic acid, has been investigated at pH 7.0 and 30.0°C. Experiments performed at different molar ratios of inhibitor/GST P1-1 indicate that 1 tool calvatic acid inactivates 1 mol GST P1-1, containing two catalytically equivalent active sites. However, 2 tool of the diazocyanide analogue of calvatic acid inactivate 1 mol GST P1-1. Two disulfide bridges/dimer, probably between Cys47 and Cys101, have been formed during the reaction of GST P1-1 with calvatic acid and its diazocyanide analogue. The apparent second-order rate constants for GST P1-1 inactivation by calvatic acid and its diazocyanide analogue are 2.4±0.3 M-1 s-1 and (8.5 ± 0.7)x 103 M-1 s-1, respectively. The reaction of calvatic acid with free L-cysteine can be described by a simple process with an apparent second-order rate constant of (5.0±0.4)x 101 M-1 s-1. In contrast, a transient species occurs during the reaction of the diazocyanide analogue of calvatic acid with free L-cysteine. Kinetics may be described by a second- order process [the rate constant being (8.0±0.5)x103 M-1 s-1] followed by a first-order decay [the rate constant corresponding to (1.2±0.1)x 101 s-1]. Calvatic acid represents an enzyme inhibitor acting much slower than its reaction intermediates (i.e. its diazocyanide analogue).

Original languageEnglish
Pages (from-to)663-667
Number of pages5
JournalEuropean Journal of Biochemistry
Volume245
Issue number3
Publication statusPublished - 1997

Fingerprint

Glutathione S-Transferase pi
Placenta
Anti-Bacterial Agents
Rate constants
Reaction intermediates
Cysteine
calvatic acid
Enzyme Inhibitors
Glutathione Transferase
Disulfides
Dimers
Catalytic Domain

Keywords

  • calvatic acid
  • cysteine oxidation
  • enzyme inhibition
  • human placenta glutathione transferase
  • kinetics

ASJC Scopus subject areas

  • Biochemistry

Cite this

Inhibition of human placenta glutathione transferase P1-1 by the antibiotic calvatic acid and its diazocyanide analogue evidence for multiple catalytic intermediates. / Antonini, Giovanni; Pitari, Giuseppina; Caccuri, Anna Maria; Ricci, Giorgio; Boschi, Donatella; Fruttero, Roberta; Gasco, Alberto; Ascenzi, Paolo.

In: European Journal of Biochemistry, Vol. 245, No. 3, 1997, p. 663-667.

Research output: Contribution to journalArticle

Antonini, G, Pitari, G, Caccuri, AM, Ricci, G, Boschi, D, Fruttero, R, Gasco, A & Ascenzi, P 1997, 'Inhibition of human placenta glutathione transferase P1-1 by the antibiotic calvatic acid and its diazocyanide analogue evidence for multiple catalytic intermediates', European Journal of Biochemistry, vol. 245, no. 3, pp. 663-667.
Antonini, Giovanni ; Pitari, Giuseppina ; Caccuri, Anna Maria ; Ricci, Giorgio ; Boschi, Donatella ; Fruttero, Roberta ; Gasco, Alberto ; Ascenzi, Paolo. / Inhibition of human placenta glutathione transferase P1-1 by the antibiotic calvatic acid and its diazocyanide analogue evidence for multiple catalytic intermediates. In: European Journal of Biochemistry. 1997 ; Vol. 245, No. 3. pp. 663-667.
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