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An. R. Acad. Nac. Farm., 2006, 72: 463-487

Artículo original

Spectrophotometric characterisation of the
Cu(II):PPi system: implementation as a method
for measuring pyrophosphate (PPi) in solution

Recibido el 15 de julio de 2006

M. FE DE LA TORRE ¹, VANESA FERNÁNDEZ-MARTÍNEZ ¹,
ÁNGEL REGLERO ¹ and IGNACIO G. BRAVO ²

¹ Dpto. Bioquímica y Biología Molecular. Universidad de León.
Campus de Vegazana. 24071. León. Spain.

² Deustches Krebsforschungszentrum. Im Neuenheimer Feld 242.
69120 Heidelberg. Germany.

ABSTRACT

The interaction of Cu(II) with pyrophosphate (PPi) in solution modifies the
absorption spectrum of the cation. We provide here a proper description of the
chemical interactions involved in the absorbance shift, identify the absorption
coefficients of the species in solution and afford a model of the Cu(II)-PPi chemical
system. Since the changes in the absorption spectrum are concentration dependent,
we describe a new method for quantifying PPi in aqueous solutions, based on the
modification of the Cu(II) absorption spectrum in the presence of PPi. Changes
in absorptivity can be monitored and used to quantify PPi in solution. The
determination is simple, fast and cheap. The detection limit of the method is
0.1 µmol of PPi in the assay conditions. The presence of orthophosphate does not
interfere in the determination of PPi. Furthermore, it is possible to use this method
in biological systems containing proteins, nucleotides, EDTA or magnesium.

Keywords: Absorption spectra.—Bioinorganic chemistry.—Spectroscopy.—
Pyrophosphate.—Copper.

Corresponding author: Prof. Dr. Ángel Reglero. Dpto. Bioquímica y Biología
Molecular. Universidad de León. Campus de Vegazana. 24071. León. Spain. Phone: +34
987 29 12 25. Fax: +34 987 29 12 26. e-mail: dbbarc@unileon.es

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