Isolation and characterization of a neurophysin from ostrich neurohypophyses

Publisher Website
Google Scholar
Abstract
A neurophysin has been isolated from ostrich neurohypophyses using acid acetone extraction, salt fractionation and Sephadex G‐75 chromatography. The crude neurophysin eluting from the Sephadex G‐75 column was subjected to a) reverse‐phase HPLC followed by Sephadex G‐75 chromatography, b) DEAE‐Sephadex A‐50 chromatography or c) isoelectric focusing. The different homogeneous ostrich neurophysin fractions so obtained were compared i.t.o. 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.