Electron transfer reaction of poly(ethylene oxide)-modified azurin in poly(ethylene oxide) oligomers

The native azurin (Az) was chemically modified with activated poly(ethylene oxide) (PEO) to solubilize in the PEO oligomers. PEO2000 (average molecula r weight of 2000)-modified Az (PEO2000-Az) was dissolved without denaturati on in PEG(200) (average molecular weight of 200). The electronic absorption spectrometry exhibited no detectable conformational change of PEO2000-Az i n phosphate buffer. The electron paramagnetic resonance (EPR) spectrum of P EO2000-Az is also quite similar to that of native Az in water. This result confirms that the chemical modification with PEG,,,, does not cause any str uctural change around the copper site. Moreover, since no changes in the EP R spectrum are observed in PE200, the copper coordination geometry must be maintained even in PEO200. The redox activity of PEO2000-Az in PEO200 (cont aining 0.5 mol dm(-3) NaClO4) was investigated by cyclic voltammetry. When we use the PEO350-SH (alpha -methoxy-omega -mercapto-poly(ethylene oxide); PEO with average molecular weight of 350) modified gold electrode as a work ing electrode, the redox response was observed in PEG,,. The result of the measurements for the scan rate dependence suggests that PEO2000-Az could be immobilized on the PEO350-SH modified electrode. (C) 2001 Elsevier Science Ltd. All rights reserved.