Cytosolic deoxyhypusine synthase (DHPS) tetramer catalyzes the reaction of of EIF5A protein, spermidine (SPM), and NAD+ to convert lysine 50 of EIF5A to deoxyhypusine (Dhp), generating 1,3 diaminopropane, NADH and H+ in the process (Clement et al. 2003; Joe et al. 1995; Park 2006; Wolff et al. 1997). Although the reaction is reversible, the reverse reaction is probably minimized under physiological conditions by the rapid, irreversible conversion of EIF5A Dhp residues to hypusine.
deoxyhypusine synthase activity of DHPS tetramer [cytosol]