Functional characterization of the amino acid hypusine

Abstract

The amino acid hypusine was first described in 1971, from bovine brain. Later, the hypusine was found in other mammalian tissues, like liver, kidney, muscle, and blood. In addition to being found in its free form, the hypusine is an amino acid residue present in eukaryotic translation initiation factor 5A (eIF5A). The eIF5A is the unique protein described that contains hypusine, produced by a post-translational modification essential for its activity. The free hypusine is derived from eIF5A degradation and it is used to form the dipeptide a-(g-aminobutyryl)-hypusine (GABA-hypusine), This dipeptide has a partial structural relationship with a-(g-aminobutyryl)-histidine (homocarnosine). Homocarnosine has antioxidant, neurotransmitter and metal chelating activity, being considered an important modulator of neuronal excitability. It is important to note that GABA is the most representative inhibitory neurotransmitter of the central nervous system. In this context, although hypusine and GABA-hypusine were discovered in the 1970s and 1980s, respectively, there is no functional information about these compounds. Thus, the present study aims to trace the cellular effects of the amino acid hypusine in neuronal cells and to evaluate the distribution of hypusine and GABA-hypusine in different tissues of mice and, aiming at the identification of potential biotechnological properties. (AU)