Purification of porcine neurophysins I and II by high performance liquid chromatography

Porcine neurophysins I and II have been reported to be metabolically active. This activity was suggested to be due to contaminations. Furthermore, neurophysin I has been suggested to be heterogeneous on the basis of amino acid sequence analysis. The neurophysins I and II were isolated from porcine pituitary glands. Though they seemed homogeneous in polyacrylamide gel- and sodium dodecyl sulfate electrophoresis, neurophysin I could be separated into neurophysin I1 and I2 by high performance liquid chromatography. Neurophysin I2 differs from neurophysin I1 by one additional C-terminal amino acid. The purified neurophysins had no metabolic activity.