Biochemical Studies of Semenogelins with Emphasis on Zinc-Binding Properties

Research output: ThesisDoctoral Thesis (compilation)

Abstract

Semenogelins I and II (SgI and SgII) are homologous and rapidly evolving proteins that have a repetitive primary structure and are synthesized mainly in the seminal vesicles. Upon ejaculation, a gelatinous coagulum is formed when the semenogelin-rich secretion from the seminal vesicles is mixed with the prostate secretion, which contains high concentrations of zinc(II) and proteases. These proteases, primarily prostate-specific antigen (PSA), begin to cleave the semenogelins, which results in liquefaction of the gel within 10 to 20 minutes.

The research findings reported in this thesis show that human SgI and SgII bind zinc(II) with a dissociation constant of 5 µM and a stoichiometry of at least ten ions per protein molecule. A truncated SgI lacking 60 amino acid residues, encoded by a polymorphic SgI-gene, was confirmed to have zinc(II)-binding capacity similar to that of the wild-type protein.

Circular dichroism spectroscopy revealed a heat stable secondary structure, and computer-based prediction of the spectra indicated that SgI (wild-type) contains 5?10% alpha-helices and 10?20% beta-sheets. The tertiary structure of SgI is changed upon binding of zinc(II), a property that may affect the ability of SgI to form a gel. Furthermore, it was discovered that the zinc(II)-binding properties of SgI enable direct measurements of the interaction between SgI and zinc(II) by surface plasmon resonance analysis.

Besides playing a structural role, zinc(II) binding to the semenogelins may have a regulatory function. It has been suggested that, by modulating the level of free zinc, the semenogelins control the activity of PSA (which is inhibited by zinc(II)). PSA can also be regulated by protein C inhibitor. Thus, a characterization of the binding between SgI and protein C inhibitor in the presence and absence of zinc(II) was carried out.
Original languageEnglish
QualificationDoctor
Awarding Institution
  • Clinical Chemistry, Malmö
Supervisors/Advisors
  • Malm, Johan, Supervisor
Award date2006 May 12
Publisher
Print ISBNs91-85481-82-3
Publication statusPublished - 2006

Bibliographical note

Defence details

Date: 2006-05-12
Time: 13:15
Place: Lilla aulan, MFC, Entrance 59, Malmö University Hospital, Malmö, Sweden

External reviewer(s)

Name: Venge, Per
Title: Professor
Affiliation: Department of Medical Sciences, Uppsala University, Sweden

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<div class="article_info">Magnus Jonsson, Sara Linse, Birgitta Frohm, Åke Lundwall and Johan Malm. <span class="article_issue_date">2005</span>. <span class="article_title">Semenogelins I and II bind zinc and regulate the activity of prostatespecific antigen.</span> <span class="journal_series_title">Biochem. J</span>, <span class="journal_volume">vol 387</span> <span class="journal_pages">pp 447-53</span>.</div>
<div class="article_info">Magnus Jonsson, Åke Lundwall, Sara Lindse, Birgitta Frohm and Johan Malm. <span class="article_issue_date"></span>. <span class="article_title">Truncated semenogelin I binds zinc and is cleaved by prostate-specific antigen.</span> <span class="journal_series_title">J. Androl.</span>, (inpress)</div>
<div class="article_info">Magnus Jonsson, Birgitta Frohm, Sara Linse and Johan Malm. <span class="article_issue_date"></span>. <span class="article_title">Binding of Zn2+ and protein C inhibitor to semenogelin I studied by surface plasmon resonance analysis</span> (manuscript)</div>
<div class="article_info">Johan Malm, Magnus Jonsson, Birgitta Frohm and Sara Linse. <span class="article_issue_date"></span>. <span class="article_title">Zn2+ changes the conformation of semenogelin I.</span> (manuscript)</div>

Subject classification (UKÄ)

  • Medicinal Chemistry

Keywords

  • sexualitet
  • sexuality
  • Obstetrik
  • gynekologi
  • andrologi
  • reproduction
  • andrology
  • gynaecology
  • Obstetrics
  • Klinisk kemi
  • Clinical chemistry
  • gel-forming proteins
  • surface plasmon resonance
  • prostate-specific antigen
  • protein C inhibitor
  • seminal plasma
  • zinc
  • semen
  • semenogelin
  • reproduktion

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