1. Laboratory of Structural Biology and Zoochemistry, Department of Biology/CEIS, Institute of Biosciences, São Paulo State University (UNESP), 13506-900, Rio Claro, SP, Brazil, Department of Chemistry, São Paulo State University (UNESP), P.O. Box 473, 17033-360, Bauru, São Paulo, Brazil, and Chemistry Institute, State University of Campinas, P.O. Box 6154, 13084-971, Campinas, SP, Brazil