Deoxyhypusine synthase (EC 2.5.1.46, spermidine:eIF5A-lysine 4-aminobutyltransferase (propane-1,3-diamine-forming)) is an enzyme with systematic name (eIF5A-precursor)-lysine:spermidine 4-aminobutyltransferase (propane-1,3-diamine-forming). This enzyme catalyses the following chemical reaction Deoxyhypusine synthase (EC 2.5.1.46, spermidine:eIF5A-lysine 4-aminobutyltransferase (propane-1,3-diamine-forming)) is an enzyme with systematic name (eIF5A-precursor)-lysine:spermidine 4-aminobutyltransferase (propane-1,3-diamine-forming). This enzyme catalyses the following chemical reaction The eukaryotic initiation factor eIF5A contains a hypusine residue that is essential for activity.