Primary structure of eel (Anguilla japonica) growth hormone

Two molecular forms of growth hormone, GHs I and II, were isolated from a culture medium of the eel pituitary (Anguilla japonica). The complete amino acid sequence of GH I was determined in the present study. The hormone was reduced, carboxymethylated, and subsequently cleaved with cyanogen bromide and enzymes. Intact eel GH I was also digested with enzyme. The resulting fragments were separated by reverse-phase high-performance liquid chromatography (HPLC) and subjected to sequence analysis by automated gas-liquid sequencer employing an Edman method. Eel GH I consists of 190 amino acid residues with two disulfide linkages formed between residues 52-163 and 180-188. Sequence comparison with other vertebrate GHs revealed that eel GH I is closer to avian and mammalian GHs with 55% identity than to salmon GH with 48% identity.