Hi, > I would like to know if there is any dna molecular building free > program that, providing the nucleotide sequence, it outputs > a first approximation to dna molecular moldel, in PDB format, > if possible. have a look at http://rutchem.rutgers.edu/~xiangjun/software.html or http://rutchem.rutgers.edu/~xiangjun/3DNA/index.html hope that helps, Michael