An electrochemical investigation of sarcolipin reconstituted into a mercury-supported lipid bilayer
Rolando Guidelli 1*, Lucia Becucci 1, Christine B. Karim 2, David D. Thomas 3 and Gianluigi Veglia 2
1 Florence University
2 University of Minnesota
3 University of Minnesota Medical School
* To whom correspondence should be addressed. E-mail: guidelli{at}unifi.it.
Submitted on March 20, 2007
Revised on April 4, 2007
Accepted on 11 June 2007
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Abstract |
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Sarcolipin was incorporated in a lipid bilayer anchored to a mercury electrode through a hydrophilic tetraethyleneoxy chain. The behavior of this tethered bilayer lipid membrane incorporating sarcolipin was investigated by electrochemical impedance spectroscopy and by recording charge versus time curves following potential jumps. When the transmembrane potential starts to become negative on the trans side, evidence is provided that sarcolipin aggregates into ion-conducting pores. Over the range of physiological transmembrane potentials, these pores are permeable to small inorganic anions such as chloride, phosphate or sulfate, but impermeable to inorganic cations such as Na+ and K+. Only at transmembrane potentials more negative than about -150 mV on the trans side, do sarcolipin channels allow the translocation of the latter cations. A tentative relationship between this property of sarcolipin and its regulatory function on Ca-ATPase of sarcoplasmic reticulum is proposed.
Key Words:
chronocoulometry, electrochemical impedance spectroscopy, ion channel, tethered BLM, thiolipid
