/his"ti deen', -din/ , n. Biochem.
an essential amino acid, C 3 H 3 N 2 CH 2 CH(NH 2 )COOH, that is a constituent of proteins and is important as the iron-binding site in hemoglobin.
Also, histidin /his"ti din/ . Abbr.: His; Symbol: H.
[ 1895-1900; HIST- + -ID 3 + -INE 2 ]