AMINO-ACID-SEQUENCE OF GROWTH-HORMONE ISOLATED FROM MEDIUM OF INCUBATED PITUITARY-GLANDS OF TILAPIA (OREOCHROMIS-MOSSAMBICUS)

The amino acid sequence of tilapia (Oreochromis mossambicus) growth hormone (GH) was determined directly by Edman degradation of peptide fragments generated by lysyl endopeptidase and trypsin digestion. The N-terminal residue was deduced to be pyroglutamic acid through the use of pyroglutamyl aminopeptidase; its removal allowed amino acid sequence determination of the remainder of the N-terminal trypsin peptide by Edman degradation. Tilapia GH is composed of 187 amino acid residues and shows high similarity to other perciform GHs. Sequence identities are: 89% with tuna GH, 83% with bonito GH, 85% with yellowtail GH, 89% with red sea bream GH, and 34% with bovine GH. The two asparagine residues (Asn-148 and Asn-184) were recovered by Edman degradation, suggesting the absence of N-glycosylation. © 1991.