Description_x000D_ Packaging_x000D_ 5, 25 mg in glass bottle_x000D_ Biochem/physiol Actions_x000D_ (2S)-Hypusine is an unusual amino acid found only in eukaryotic translation initiation factor 5A (eIF5A) and a similar protein in archaebacteria. (2S)-Hypusine is formed by posttranslational modification of a lysine with the addition of the 4-aminobutyl moiety from the polyamine spermidine. There is increasing interest in the polyamine-hypusine axis and eIF5A, its a role in cell growth and differentiation, and a recent paper on the polyamine-hypusine axis as a potential new tumour suppressor network.