a peptide containing 43 amino acid residues , rich in glutamic acid and lysine , was originally isolated from calf thymus and designated thymosin beta 4 [ t.l.k . low , s. -k. hu , and a. l. goldstein ( 1981 ) proc . nat . acad . sci . usa 78 , 1162-1166 ] .
C0002520
amino acid
C0061472
glutamic acid