Hydralazine inhibition of the post-translational hydroxylation of deoxyhypusine, a polyamine-derived amino acid.

Logarithmically growing Chinese hamster ovary cells, cultured in the presence of [1,4-14C]putrescine, synthesize a protein(s) containing the unusual amino acid hypusine [N epsilon-(4-amino-2-hydroxybutyl)lysine]. This protein was separated and identified by two-dimensional gel electrophoresis and fluorography. The labeled hypusine isolated from an acid hydrolysate of the cell protein by ion exchange chromatography was identified by oxidative degradation and analyses of the products. Hydralazine, one of the most frequently prescribed drugs for the treatment of moderate to severe hypertension, added to the culture, resulted in the accumulation of a protein(s) containing the precursor amino acid deoxyhypusine [N epsilon-(4-aminobutyl)lysine]. Demonstration of this intermediate and its subsequent conversion to hypusine suggests that the synthesis occurs in several steps, one of these involving a hydroxylation reaction which can be inhibited by hydralazine.