History of various concepts of Protein By Gboogy14 Period: 1800 to 1950 History of various concepts of Protein 1809 Asparagine discovered Period: 1809 to 1936 History of various concepts of Protein 1819 Leucine discovered 1868 RNA was discovered The year RNA was discovered. 1869 DNA was discovered DNA (double-helix) was discovered. 1901 Valine was discovered The year the protein Valine was isolated 1902 Peptide bond was discovered 1936 Threonine discovered