2944563 L-ENK leucine-enkephalin 72 2898182 Leu-Enk leucine-enkephalin 69 245083 LE leucine enkephalin 44 3894748 Leu-enkephalin leucine-enkephalin 13 921047 ENK leucine-enkephalin 11 1165664 LEK leucine-enkephalin 10 1165660 L-Ek leucine-enkephalin 9 2898185 LeuEnk leucine enkephalin 7 1165658 L-EK leucine-enkephalin 4 140159 EK leucine-enkephalin 3 2944565 Lenk leucine-enkephalin 3 1025975 leu-EK leucine-enkephalin 2 244792 L-E leucine-enkephalin 1 1167145 LEU leucine-enkephalin 1 1024889 leu-Ap leucine-enkephalin 1