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A simple strategy for electrochemical study of proteins avoiding metallic groups

C.A.Ferreira, R.S.Henrique, M.R.P.L.Brigag�?�?�?�?�?�?�?£o, J.M.Schneedorf*

A simple strategy for studying electrochemical properties of proteins or peptides using unmodified carbon paste electrodes was developed by cross-linking dopamine (DA) with BSA as a test protein. The BSA-5-Cys- DAadducts produced were evaluated by cyclic voltammetry, spectrofluorometry and first-derivative spectrophotometry in the visible range. An anodic peak was observed after protein isolation, not found with BSA samples only. This approach allow to overlap the sluggish kinetics of electron transfer exhibited by proteins with no metallic prosthetic groups near the electrode surface, providing thermodynamic and conformational studies by electrochemical techniques. A marked increased in fluorescence signal at 350 nm emission together with the appearance of an absorption signal at 370 nmhave also arisen fromthe protein adducts. In this sense the covalent linkage between BSA with dopamine disclosed it as a dual candidate for both electrochemical and spectroscopic studies of proteins either in solution or immobilized on electrode surfaces.