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A neurophysin has been isolated from ostrich neurohypophyses using acid acetone extraction, salt fractionation and Sephadex (2-75 chromatography. The crude neurophysin eluting from the Sephadex (2-75 column was subjected to a) reverse-phase HPLC followed by Sephadex (2-75 chromatography, b) DEAE-Sephadex A-50 chromatography or c) isoelectric focusing. The different homogeneous ostrich neurophysin fractions so obtained were compared i.t.0. amino acid composition, spectral properties, N-terminal amino acid residues and PAGE. They all revealed a single N-terminal Ala residue and displayed spectral properties (A280 /A260 < 1) which are typical of mammalian neurophysin-like polypeptides. Ultracentrifugation studies on purified ostrich neurophysin over a range of concentrations revealed a reversible concentration dependent association behaviour characterized by the presence of dimeric complexes at higher concentrations. Partial sequencing from the N-terminus revealed the molecule to be VLDV-like. The purified molecule was also submitted to CNBr fragmentation.

Mammalian neurohypophyseal hormones, oxytocin and vasopressin, are known to be synthesized as part of two larger precursors containing, respectively, a VLDV-neurophysin and a MSEL-neurophysin together with its associated glycopeptide. Starting from ostrich neurohypophyses, a "big" neurophysin was isolated and chemically characterized. Following sequence determination of the CNBr-derived fragments and of peptides obtained from trypsin and V8-protease digestion of the oxidized protein, this "big" neurophysin was found to contain an MSEL-neurophysin moiety (94 residues) still covalently associated with the COOH-terminal glycopeptide (38 residues, copeptin). This study demonstrates that the ostrich MSEL-neurophysin sequence cIosely resembles all known MSEL-neurophysin sequences and that, furthermore, it does not contain the single amino acid insertion shown previously in the ostrich VLDV-neurophysin. It is also shown that the stretch of amino acids, linking the MSEL-neurophysin and the copeptin, is clearly different from its mammalian homologues and lacks the Arg residue normally recognized by the cleaving enzyme. This study also demonstrates that the ostrich copeptin is more closely related to the amphibian copeptin sequence than to its mammalian homologue, leading to the hypothesis that two families of copeptin molecules might exist. Thus, the ostrich MSEL-neurophysin-copeptin molecule is the first "big" neurophysin reported in birds and, together with the guinea pig and amphibian homologues, represents the third example of partial or no neurophysin-copeptin cleavage.

Ghcagon is a highly conserved polypeptide hormone which appears to play a more important role in regulation of glycaernia in birds than insulin. Ostrich glucagon was isolated and purified from ostrich pancreas splenic lobes using an adapted acid ethanol extraction procedure, gel filtration, ion exchanges, and HPLC steps. The purified glucagon fraction appeared to contain small quantities of a more acidic contaminant (polyacrylamide gel isoelectric focussing, PAGE) but appeared homogeneous on SDS-PAGE. Amino acid analysis and sequence analysis showed identity with the duck hormone. Identity with the duck hormone was confirmed by liquid phase as well as gas phase sequencing. The ostrich glucagon preparation seemed to have a higher K, than the porcine homologue in stimulating glyccrol rclcasc from isolated chicken adipocytes Kej, words: glucagon: lipolysis: ostrich

The neurohypophyseal hormones vasopressin and oxytocin are known to be synthesized in eutherian mammals as part of larger precursors containing either MSEL‐or VLDV‐neurophysins. A neurophysin has been isolated from ostrich neurohypophyses and shown by partial amino acid sequence determination to be related to mammalian VLDV‐neurophysin. The present report describes the complete amino acid sequence of this ostrich neurophysin containing 93 residues. This amino acid sequence, the first reported in birds, differs in a remarkable manner from its mammalian homolog. Indeed, it contains a large number of substitutions, including one insertion, distributed throughout the polypeptide chain when compared to known VLDV‐neurophysins. Whereas many of these substitutions are localized inside the so‐called constant region of the neurophysin, the highest variation can be found in the COOH‐terminal region.