Isolation and characterization of [Pro2]somatostatin-14 and melanotropins from Russian sturgeon, Acipenser gueldenstaedti Brandt.

A new form of somatostatin (SRIH), along with melanotropins (MSHs), was isolated from pituitaries of the Russian sturgeon Acipenser gueldenstaedti Brandt by gel filtration, ion exchange, and reversed-phase HPLC following acid-acetone extraction. The sturgeon SRIH consists of 14 amino acid residues and differs from mammalian SRIH-14 by the substitution Pro for Gly at position 2. Synthetic [Pro2]SRIH-14 was as potent as mammalian SRIH-14 in inhibiting release of growth hormone into medium from the organ-cultured pituitary of rainbow trout. Sturgeon alpha-MSH has the same amino acid sequence as those found in mammals. Sturgeon beta-MSH is composed of 17 amino acid residues, and its amino acid sequence is identical to the N-terminal 15 residues of salmon beta-MSH I and to the C-terminal 2 residues of mammalian beta-MSH.