Complete amino acid sequence of crocodile growth hormone

This paper describes the isolation and complete amino acid sequence of growth hormone (GH) from the pituitary gland of the crocodile, Crocodylus novaeguineae. GH was detected in an alkaline extract of the pituitary by specific immunoblot reactivity with rabbit antisera against cattle and salmon GH and isolated in pure form by DEAE-cellulose chromatography and by reversed-phase high-performance liquid chromatography. The yield of the GH was 2.2 mg from 3.5 g of wet tissue. Crocodile GH consists of 190 residues and is highly similar to chicken, duck, and sea turtle GHs with 90-92% structural similarity, although it shows only 27% identity with crocodile prolactin. A molecular phylogenetic tree of GH from 39 vertebrate species is proposed on the basis of sequence comparison.