Occurrence of two different endorphins in the salmon pituitary

Two endorphins have been identified in the teleost pituitary, $\text{Oncorhynchus}\text{keta}$ (chum salmon). Endorphin I is a nonacosa peptide and the primary structure was reported previously. Endorphin II has been elucidated to be a triaconta peptide with the following primary structure: Ac-Tyr-Gly-Gly- Phe-Met-Lys-Ser-Trp-Asn-Glu-Arg-Ser-Gln-Lys-Pro-Leu-Leu-Thr- Leu-Phe-Lys-Asn-Val-Ile-Ile-Lys-Asp-Gly-Gln-Gln-OH. It is evident that these endorphins are highly homologous to each other, but are different molecules, and that endorphin II is much more similar to the mammalian endorphins than endorphin I.