An EPR Method for Studying Annexin-Biomembrane Interaction

Annexin p34 spin label has been used as a probe for studying annexin-membrane Ca-mediated interaction. The EPR spectrum of the purified probe is able to monitor the binding of the protein to phospholipid vesicles and isolated mitochondrial membranes, with increasing calcium concentration, as revealed by the calculated rotational correlation time. A novel mathematical approach is proposed to provide a direct estimation of annexin percentage binding to membranes, based on the correlation time calculated from experimental EPR spectra.