Pronunciation: [hˈa͡ɪpjuːsˌa͡ɪn] (IPA) 
The word "hypusine" is spelled with a silent "h" at the beginning, pronounced as /haɪˈpjuːsɪn/. The sound represented by "y" in the spelling is pronounced as /juː/ or "you". The letter "s" is pronounced as /s/, while the letter "i" is pronounced as /ɪ/ or "ih". The final "e" at the end of the word is pronounced as /iː/ or "ee". Hypusine is a rare amino acid found in eukaryotic cells, essential for proper cellular function.
Hypusine is a naturally occurring amino acid modification that plays a crucial role in the function and stability of certain proteins. Specifically, it is a post-translational modification of the amino acid lysine, which involves the addition of a unique polyamine called spermidine. This modification is catalyzed by the enzyme deoxyhypusine synthase (DHPS), often referred to as DHS, and requires the precursor amino acid, spermidine, and the enzyme deoxyhypusine hydroxylase (DOHH) to complete the process.
Hypusine modification typically occurs in a specific group of proteins known as eukaryotic initiation factor 5A (eIF5A) proteins. These proteins are involved in various cellular processes, including translation initiation, protein synthesis, and cell proliferation. The addition of hypusine to eIF5A is crucial for its functional activity and stability.
The significance of hypusine lies in its ability to regulate the synthesis of essential proteins involved in cell growth and proliferation. Furthermore, hypusine modification has been linked to various diseases, including cancer, neurodegenerative disorders, and viral infections. Understanding the mechanisms and pathways associated with hypusine modification has become a topic of great interest in biomedical research, as it may provide insights into potential therapeutic targets for treating these diseases.
In summary, hypusine is a unique post-translational modification of the amino acid lysine that plays a crucial role in the function and stability of eIF5A proteins. It is catalyzed by the enzymes DHS and DOHH, and its presence is essential for cellular processes such as protein synthesis, cell growth, and proliferation.
The etymology of the word "hypusine" can be traced back to its Greek origins. The term "hypusine" is derived from the Greek word "hypoúsios", meaning "under the substance" or "below the essence". It was coined by researchers who were studying the unique modification of a specific amino acid called lysine. This modification process involves the attachment of the organic compound spermidine to the lysine residue in a protein, forming what is known as the hypusine residue. This discovery and subsequent naming of the hypusine modification occurred in the late 1970s and early 1980s.
