[1] Consejo Nacl Invest Cient & Tecn, Inst Leloir, RA-1405 Buenos Aires, DF, Argentina
[2] Consejo Nacl Invest Cient & Tecn, IIBBA, RA-1405 Buenos Aires, DF, Argentina
[3] Univ Bristol, Sch Med Sci, Dept Biochem, Bristol BS8 1TH, Avon, England
[4] Univ Roma Tor Vergata, Dept Sci & Chem Technol, I-00133 Rome, Italy