[1] UNIV ROMA TOR VERGATA,DIPARTIMENTO BIOL,I-00133 ROME,ITALY
[2] UNIV MESSINA,DIPARTIMENTO CHIM ORGAN & BIOL,I-98166 MESSINA,ITALY
[3] DESY,EUROPEAN MOLEC BIOL LAB,D-22603 HAMBURG,GERMANY
[4] UNIV GENOA,CTR BIOTECNOL AVANZATE,I-16132 GENOA,ITALY
[5] UNIV GENOA,DIPARTIMENTO FIS,I-16132 GENOA,ITALY