Characterization of Sperm Immobilization Factor from Escherichia coli and Its Receptor to Study the Underlying Mechanism of Sperm Immobilization

Department of Microbiology, Panjab University, Chandigarh, India

*Corresponding Author:

Dr. (Mrs) Vijay Prabha

Professor

Department of Microbiology

Panjab University

Chandigarh-160014.

India

Telephone: 91-172-2534140

Fax: 91-172-2541770

E mail: satishvijay11@yahoo.com

Abstract

       Sperm immobilization factor (SIF) was extracted and purified from Escherichia coli filtrate. Characterization of SIF using Liquid chromatography -mass spectrometry (LC-MS) revealed its sequence similarity to chaperone protein HchA of E. coli O157:H7. Further the effect of SIF on sperm functions such as acrosome reaction was studied and the results showed that SIF (500μg/ml) significantly inhibits calcium ionophore induced acrosome reaction. SIF was also found to decrease Mg⁺⁺ ATPase activity of spermatozoa from 869.5 (control) to zero at 25μg/ml. The corresponding SIF binding receptor was also isolated and purified. The tryptic peptide analysis of SIF binding receptor by MALDI-TOF (Matrix assisted laser desorption ionization- time of flight) showed its sequence similarity to chain A structure of human apolactoferrin. Further specificity of SIF and SIF binding receptor was studied by calorimetric studies that showed binding constant (κ), enthalpy of binding (ΔH⁰), free energy (ΔG) and entropy (ΔS) to be 1460/M and -11.7kJ/mole, -18.76 kJ/mole and 22.77 J/moleK, respectively.

Keywords: Escherichia coli, sperm immobilization factor, spermatozoa, receptor, acrosome reaction.

Download the full article (PDF)