1) Amino acid 
Hypusine is an unusual amino acid found in all eukaryotes and in some archaea, but not in bacteria. The only known protein containing hypusine is eukaryotic translation initiation factor 5A (eIF5A) and a similar protein found in archaebacteria. In humans, two isoforms of eIF-5A have been described: eIF5A-1 and eIF5A-2. They are encoded by two diff...