Despite a number of studies, the formation of the Michaelis complexes between ferredoxin-NADP (+) reductases and NADP(H) eluded detailed investigations by rapid kinetic techniques because of their high formation rates. Moreover, the reversible nature of the reaction of hydride ion transfer between these enzymes and NADPH prevented the obtainment of reliable estimates of the rate constant of the hydride transfer step. Here we show that by working at a high salt concentration, the mechanism of the reaction with NADPH of FprA, a Mycobacterium tuberculosis homologue of adrenodoxin reductase, is greatly simplified, making it amenable to investigation by rapid reaction techniques. The approach presented herein allowed for the first time the observation of the formation of the Michaelis complex between an adrenodoxin reductase-like enzyme and NADPH, and the determination of the related rate constants for association and dissociation. Furthermore, the rate constant for the reaction of hydride ion transfer between NADPH and FAD could be unambiguously assessed. It is proposed that the approach described should be applicable to other ferredoxin reductase enzymes, providing a valuable experimental tool for the study of their kinetic properties.

Effect of salt and pH on the reductive half-reaction of Mycobacterium tuberculosis FprA with NADPH / A. Pennati, G. Zanetti, A. Aliverti, G. Gadda. - In: BIOCHEMISTRY. - ISSN 0006-2960. - 47:11(2008), pp. 3418-3425. [10.1021/bi702250h]

Effect of salt and pH on the reductive half-reaction of Mycobacterium tuberculosis FprA with NADPH

A. Pennati
Primo
;
G. Zanetti
Secondo
;
A. Aliverti
Penultimo
;
2008

Abstract

Despite a number of studies, the formation of the Michaelis complexes between ferredoxin-NADP (+) reductases and NADP(H) eluded detailed investigations by rapid kinetic techniques because of their high formation rates. Moreover, the reversible nature of the reaction of hydride ion transfer between these enzymes and NADPH prevented the obtainment of reliable estimates of the rate constant of the hydride transfer step. Here we show that by working at a high salt concentration, the mechanism of the reaction with NADPH of FprA, a Mycobacterium tuberculosis homologue of adrenodoxin reductase, is greatly simplified, making it amenable to investigation by rapid reaction techniques. The approach presented herein allowed for the first time the observation of the formation of the Michaelis complex between an adrenodoxin reductase-like enzyme and NADPH, and the determination of the related rate constants for association and dissociation. Furthermore, the rate constant for the reaction of hydride ion transfer between NADPH and FAD could be unambiguously assessed. It is proposed that the approach described should be applicable to other ferredoxin reductase enzymes, providing a valuable experimental tool for the study of their kinetic properties.
site-directed mutagenesis; human cytochrome-P450 reductase; X-ray crystallography; adrenodoxin reductase; electron-transfer; catalytic mechanism; ferrodixin-NADP(+) reductase; active-site; specificity; complexes
Settore BIO/10 - Biochimica
Article (author)
File in questo prodotto:
File Dimensione Formato  
FprA Pennati ionic strength pH 2008_Biochemistry.pdf

accesso riservato

Descrizione: Articolo completo
Tipologia: Publisher's version/PDF
Dimensione 1.04 MB
Formato Adobe PDF
1.04 MB Adobe PDF   Visualizza/Apri   Richiedi una copia
Pubblicazioni consigliate

I documenti in IRIS sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.

Utilizza questo identificativo per citare o creare un link a questo documento: https://hdl.handle.net/2434/38191
Citazioni
  • ???jsp.display-item.citation.pmc??? 3
  • Scopus 3
  • ???jsp.display-item.citation.isi??? 4
social impact