作者单位:Univ Fed Rio de Janeiro, Nucl Magnet Resonance Natl Ctr, Rio De Janeiro, Brazil[1]Univ Fed Sao Paulo, Dept Biophys, Sao Paulo, Brazil[2]Univ Fed Minas Gerais, Dept Chem, Belo Horizonte, MG, Brazil[3]Univ Sao Paulo, Dept Biochem, Sao Paulo, Brazil[4]