Structural properties of semenogelin I.

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The zinc-binding protein semenogelin I is the major structural component of the gelatinous coagulum that is formed in freshly ejaculated semen. Semenogelin I is a rapidly evolving protein with a primary structure that consists of six repetitive units, each comprising approximately 60 amino acid residues. We studied the secondary and tertiary structure of semenogelin I by circular dichroism (CD) spectroscopy and Trp fluorescence emission spectroscopy. Fitting to the far-UV CD data indicated that the molecule comprises 5-10%alpha-helix and 20-30%beta-sheet formations. The far-UV spectrum of semenogelin I is clearly temperature dependent in the studied range 5-90 degrees C, and the signal at 222 nm increased with increasing temperature. The presence of Zn2+ did not change the secondary structure revealed by the far-UV CD spectrum, whereas it did alter the near-UV CD spectrum, which implies that rearrangements occurred on the tertiary structure level. The conformational change induced in semenogelin I by the binding of Zn2+ may contribute to the ability of this protein to form a gel.
Original languageEnglish
Pages (from-to)4503-4510
JournalThe FEBS Journal
Issue number17
Publication statusPublished - 2007

Subject classification (UKÄ)

  • Biochemistry and Molecular Biology

Free keywords

  • fertility
  • semen
  • semenogelin
  • zinc
  • structure


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