4-Guanidinobutanoic acid is primarily used in biochemical research as a precursor or intermediate in the synthesis of more complex molecules. It plays a role in studying enzyme mechanisms, particularly those involving arginine metabolism, due to its structural similarity to arginine. Additionally, it is utilized in the development of pharmaceutical compounds, especially those targeting nitric oxide pathways, as it can influence nitric oxide synthase activity. Its applications also extend to the field of peptide synthesis, where it serves as a building block for creating modified peptides with potential therapeutic properties.