Binding of [Cr(phen)3]3+ to transferrin at extracellular and endosomal pHs: Potential application in photodynamic therapy

P. F. GARCIA; J. TONEATTO; J. SILVERO; G. A. ARGÜELLO

ELSEVIER SCIENCE BV

Lugar: Amsterdam; Año: 2014

ackgroundTransferrin is an iron-binding blood plasma glycoprotein that controls the level of free iron in biological fluids. This protein has been deeply studied in the past few years because of its potential use as a strategy of drug targeting to tumor tissues. Chromium complex, [Cr(phen)3]3+ (phen = 1,10-phenanthroline), has been proposed as photosensitizers for photodynamic therapy (PDT). Thus, we analyzed the binding of chromium complex, [Cr(phen)3]3+, to transferrin for a potential delivery of this diimine complex to tumor cells for PDT.MethodsThe interaction between [Cr(phen)3]3+ and holotransferrin (holoTf) was studied by fluorescence quenching technique, circular dichroism (CD) and ultraviolet (UV)?visible spectroscopy.Results[Cr(phen)3]3+ binds strongly to holoTf with a binding constant around 105 M−1, that depends on the pH. The thermodynamic parameters indicated that hydrophobic interactions played a major role in the binding processes. The CD studies showed that ther