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PubMed1994

Staphylococcal protein A containing phospholipid monolayers on aqueous and solid surfaces.

The staphylococcal protein A containing monolayer is characterized on both aqueous and solid surfaces. The density of SpA in dipalmitoylphosphatidic acid (DPPA) monolayers is determined from ultraviolet spectroscopy. The influence of calcium on the SpA concentration in the monolayer is also investigated. The spectroscopic results indicate that the incorporation of SpA in the monolayer is influenced by the calcium concentration in the subphase, and more than 90% of adsorbed protein is excluded from the monolayer when calcium concentration is in the order of millimoles. The IgG binding activity of the SpA in the reconstituted membrane is influenced by the surface pressure at which the membrane is formed.

Calcium↗

PubMed1994

Characterization of modified staphylococcal protein A containing phospholipid monolayer on both solution and slide surfaces.

A method is described for incorporation of water-soluble protein Staphylococcal protein A (SpA) into phospholipid monolayer using covalent protein-lipid conjugates in detergent solution. The amphiphilic conjugates have solubility properties very similar to intergral membrane proteins. When the conjugates are applied into dipalmitoyl-phosphatidic acid monolayer, a protein containing monolayer is formed on subphase surface. The monolayer is transferred to pre-coated substrate surface to form an artificial membrane. Results show that unmodified SpA is readily ejected from the monolayer when compressing the monolayer but modified SpA incorporates into the monolayer stably. The incorporation of the protein is proportional to the lipid coupling degree. When the protein is excessively modified, the IgG binding activity of the SpA in the membrane is lost significantly.

Immunoglobulin G↗