A voltammetric study of the binding of copper(II) to peptide fragments of prion |
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| Authors: | Clarissa Silva Pires de Castro Jurandir Rodrigues SouzaDe Marcelo Porto Bemquerer Waldemar Pacheco de Oliveira Filho |
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| Institution: | 1. Laboratório de Espectrometria de Massa, Embrapa Recursos Genéticos e Biotecnologia, P.O. Box 02372, 70.770-917 Brasília, DF, Brazil;2. Laboratório de Química Analítica e Ambiental, Instituto de Química, Universidade de Brasília, P.O. Box 04394, 70.919-970 Brasília, DF, Brazil;3. Departamento de Bioquímica e Imunologia, Instituto de Ciências Biológicas, Universidade Federal de Minas Gerais, P.O. Box 486, 31.270-901 Belo Horizonte, MG, Brazil |
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| Abstract: | Binding of copper to three peptide fragments of prion (Cu2+ binding sites: 60–91, 92–96 and 180–193 amino acid residues) was investigated by anodic stripping voltammetry to determine the stoichiometries of Cu2+-prion peptide interactions. The method relies on the synthesis of N-terminally acetylated/C-terminally amidated peptide fragments of prion by solid-phase synthesis and direct monitoring of the oxidation current of copper in the absence and presence of each prion fragment. Titration curves of Cu2+ with Ac-PHGGGWGQ-NH2, Ac-GGGTH-NH2 and Ac-VNITKQHTVTTTT-NH2 were obtained in concentrations ranging from 8.52 × 10?7 to 5.08 × 10?6, 3.95 × 10?7 to 1.94 × 10?6 and 7.82 × 10?8 to 4.51 × 10?7 M, respectively. The acquired data were used to calculate the stoichiometries (one peptide per Cu2+ ion for all the three studied systems) and apparent dissociation constants (Kd = 4.37 × 10?8–3.50 × 10?10 M) for the three complexes. |
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