Biophysical investigations on the interaction of the major bovine seminal plasma protein, PDC-109, with heparin

Sankhala, Rajeshwer S. ; Damai, Rajani S. ; Anbazhagan, V. ; Kumar, Sudheer C. ; Bulusu, Gopalakrishnan ; Swamy, Musti J. (2011) Biophysical investigations on the interaction of the major bovine seminal plasma protein, PDC-109, with heparin Journal of Physical Chemistry B, 115 (44). pp. 12954-12962. ISSN 1520-6106

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Official URL: http://pubs.acs.org/doi/abs/10.1021/jp203509r

Related URL: http://dx.doi.org/10.1021/jp203509r

Abstract

PDC-109, the major bovine seminal plasma protein, binds to sperm plasma membrane and modulates capacitation in the presence of heparin. In view of this, the PDC-109/heparin interaction has been investigated employing various biophysical approaches. Isothermal titration calorimetric studies yielded the association constant and changes in enthalpy and entropy for the interaction at 25 °C (pH 7.4) as 1.92 (±0.2) × 105 M–1, 18.6 (±1.6) kcal M–1, and 86.5 (±5.1) cal M–1 K–1, respectively, whereas differential scanning calorimetric studies indicated that heparin binding results in a significant increase in the thermal stability of PDC-109. The affinity decreases with increase in pH and ionic strength, consistent with the involvement of electrostatic forces in this interaction. Circular dichroism spectroscopic studies indicated that PDC-109 retains its conformational features even up to 70–75 °C in the presence of heparin, whereas the native protein unfolds at about 55 °C. Atomic force microscopic studies demonstrated that large oligomeric structures are formed upon binding of PDC-109 to heparin, indicating an increase in the local density of the protein, which may be relevant to the ability of heparin to potentiate PDC-109 induced sperm capacitation.

Item Type:Article
Source:Copyright of this article belongs to American Chemical Society.
ID Code:95848
Deposited On:07 Dec 2012 06:18
Last Modified:07 Dec 2012 06:18

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