Acrosome reaction inducers impose alterations in repulsive strain and hydration barrier in human sperm membranes

Sharad B Purohit, Malini Laloraya, G. Pradeep Kumar

Research output: Contribution to journalArticle

9 Scopus citations

Abstract

Spin labeling studies of the lipophilic domains of human spermatozoa during capacitation and during acrosome reaction (AR) under the influence of selected AR-inducers were performed. Significantly enhanced rotational function of molecules was obvious during capacitation, with no significant changes in membrane packaging or the lateral diffusion of molecules. The AR inducers appeared to restrict the rotational freedom of molecules, dramatically enhancing the lateral diffusion and ordering coefficients. A significant decrease in superoxide anion generation was observed in the acrosome reacted groups when compared to the non-acrosome reacted groups. A high level of superoxide anion radical (O 2 .- ) level maintained in capacitated spermatozoa would add to the Van der Waal's repulsive forces at the polar head of phospholipids, holding the membrane in strain where the molecular enjoy little freedom for lateral motion. A sudden drop in the levels of O 2 .- in spermatozoa upon addition of AR inducers could abruptly release the local hydrophobic repulsive strain within the membrane. This loss of hydration barrier explains the observed enhancement in lateral diffusion profiles of lipids and the packaging of molecules. It is reasonable to assume that these phenomena could be amplified further by interplay of Ca 2+ by modifying the local charge aggregation. Thus, we would conclude that AR inducers release the oxyradical load in capacitated spermatozoa, which would modify the repulsive strain and hydration barrier forces in the lipophilic domains permitting vesiculation of the membranes. It appears that various acrosome reaction inducers act as effecters of grossly similar physical alterations in sperm membranes and that the resulting signal cascades proceed through intercalating biochemical sequences.

Original languageEnglish (US)
Pages (from-to)227-235
Number of pages9
JournalBiochemistry and Molecular Biology International
Volume45
Issue number2
StatePublished - Jun 1 1998
Externally publishedYes

Keywords

  • Acrosome reaction
  • Capacitation
  • Membrane fluidity
  • Spermatozoa
  • Spin labeling

ASJC Scopus subject areas

  • Biochemistry
  • Molecular Biology
  • Genetics

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