Purification and characterization of human deoxyhypusine synthase from HeLa cells

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Abstract
Post‐translational modification of a specific lysine residue in eukaryotic initiation factor 5A is essential for cell viability. The amino acid hypusine, which is the product of this modification, is derived in two subsequent enzyme‐catalyzed reactions. We have purified and characterized the enzyme responsible for the first step in hypusine modification, deoxyhypusine synthase, from HeLa cells. The human enzyme is multimeric with a native apparent molecular weight of 150,000 consisting of subunits of 41,000. The amino acid sequences of its peptide fragments share high sequence identity with a hypothetical protein (YHRO68w) on chromosome VIII ofSaccharomyces cerevisiae. This protein appears to be the deoxyhypusine synthase of yeast.