In addition, while the conformation of IdoA can be either a 4C1 chair or 2S0 skew boat form, GlcA prefers a 4C1 conformation,57 suggesting that 2-O-sulfated uronic acids in the 4C1 conformation might play an important role in the inhibition of S. pneumoniae adhesion onto FN fibrils and corneal infection. This evidence concerns the gene FN1 and corneal infection.