title: Enhanced adsorption of Ca-ATPase containing vesicles on a negatively charged solid-supported-membrane for the investigation of membrane transporters.
abstract: A convenient model system for a biological membrane is a solid-supported membrane (SSM), which consists of a gold-supported alkanethiol|phospholipid bilayer. In combination with a concentration jump method, SSMs have been used for the investigation of several membrane transporters. Vesicles incorporating sarcoplasmic reticulum Ca-ATPase (SERCA) were adsorbed on a negatively charged SSM (octadecanethiol|phosphatidylserine bilayer). The current signal generated by the adsorbed vesicles following an ATP concentration jump was compared to that produced by SERCA-containing vesicles adsorbed on a conventional SSM (octadecanethiol|phosphatidylcholine bilayer). A significantly higher current amplitude was recorded on the serine-based SSM. The adsorption of SERCA-incorporating vesicles on the SSM was then characterized by surface plasmon resonance (SPR). The SPR measurements clearly indicate that in the presence of Ca(2+) and Mg(2+), the amount of adsorbed vesicles on the serine-based SSM is about twice that obtained using the conventional SSM, thereby demonstrating that the higher current amplitude recorded on the negatively charged SSM is correlated with a greater quantity of adsorbed vesicles. The enhanced adsorption of membrane vesicles on the PS-based SSM may be useful to study membrane preparations with a low concentration of transport protein generating small current signals, as in the case of various recombinantly expressed proteins.
authors.affiliation: Department of Chemistry "Ugo Schiff", University of Florence , via della Lastruccia 3, 50019 Sesto Fiorentino, Italy.
authors.forename: Alessio
authors.initials: A
authors.lastname: Sacconi
authors.forename: Maria Rosa
authors.initials: MR
authors.lastname: Moncelli
authors.forename: Giancarlo
authors.initials: G
authors.lastname: Margheri
authors.forename: Francesco
authors.initials: F
authors.lastname: Tadini-Buoninsegni
mesh_terms: D000327:Adsorption; D000818:Animals; D019556:COS Cells; D002118:Calcium / Q000378:metabolism; D000252:Calcium-Transporting ATPases / Q000378:metabolism*; D002522:Chlorocebus aethiops; D004563:Electrochemistry; D008274:Magnesium / Q000378:metabolism; D008567:Membranes, Artificial; D012519:Sarcoplasmic Reticulum / Q000737:chemistry* / Q000378:metabolism*; D020349:Surface Plasmon Resonance
chemical_list: D008567:Membranes, Artificial; D000252:Calcium-Transporting ATPases; D008274:Magnesium; D002118:Calcium