Isolation of intact transition protein 4 from boar late spermatid nuclei

Boar transition protein 4 was extracted with acid from the late spermatid nuclei, and separated from the transition protein-degrading proteases by ion-exchange chromatography on Fractogel EMD SO3- 650 (M). The transition protein was further purified by HPLCs on Nucleosil 300 7C18 and Diol-200. The circular dichroic spectra of the protein with and without dithiothreitol showed that the protein had beta-form predominantly. Although sodium dodecyl sulfate affected the tertially structure of the protein, the beta-form was well retained. These indicate that the protein has a structure-forming potential for the beta-structure.