Artículos de revistas
Catalytic properties of thioredoxin immobilized on superparamagnetic nanoparticles
Fecha
2011Registro en:
JOURNAL OF INORGANIC BIOCHEMISTRY, v.105, n.5, p.738-744, 2011
0162-0134
10.1016/j.jinorgbio.2011.02.006
Autor
NETTO, Caterina G. C. M.
NAKAMATSU, Eduardo H.
NETTO, Luis E. S.
NOVAK, Miguel A.
ZUIN, Andre
NAKAMURA, Marcelo
ARAKI, Koiti
TOMA, Henrique E.
Institución
Resumen
Thioredoxin (Trx1), a very important protein for regulating intracellular redox reactions, was immobilized on iron oxide superparamagnetic nanoparticles previously coated with 3-aminopropyltriethoxysilane (APTS) via covalent coupling using the EDC (1-ethyl-3-{3-dimethylaminopropyl}carbodiimide) method. The system was extensively characterized by atomic force microscopy, vibrational and magnetic techniques. In addition, gold nanoparticles were also employed to probe the exposed groups in the immobilized enzyme based on the SERS (surface enhanced Raman scattering) effect, confirming the accessibility of the cysteines residues at the catalytic site. For the single coated superparamagnetic nanoparticle, by monitoring the enzyme activity with the Ellman reagent, DTNB=5,5`-dithio-bis(2-15 nitrobenzoic acid), an inhibitory effect was observed after the first catalytic cycle. The inhibiting effect disappeared after the application of an additional silicate coating before the AFTS treatment, reflecting a possible influence of unprotected iron-oxide sites in the redox kinetics. In contrast, the doubly coated system exhibited a normal in-vitro kinetic activity, allowing a good enzyme recovery and recyclability. (C) 2011 Elsevier Inc. All rights reserved.