title: Adsorption of vitamin K-dependent blood coagulation proteins to spread phospholipid monolayers as determined from combined measurements of the surface pressure and surface protein concentration.
abstract: Spread phospholipid monolayers are particularly useful as model membranes in that changes in surface pressure (Deltapi) can be monitored in response to protein adsorption to the monolayer, thus providing a unique manner of assessing protein-membrane contact. In the present study, spread monolayers below their collapse pressures have been utilized to evaluate Ca2+-specific adsorption of several vitamin K-dependent coagulation proteins to monolayers that contain negatively charged phospholipid. From combined measurements of Deltapi and Gamma (the surface excess protein concentration), values of dGamma/dpi have been evaluated for different proteins with varying lipid composition of the monolayers. Using mixed, liquid-expanded monolayers at equivalent initial surface pressures (pii) and which contain different amounts of phosphatidylserine, phosphatidylcholine, and phosphatidylethanolamine, the dGamma/dpi of bovine prothrombin was shown to decrease monotonically with increasing protein affinity for the monolayer. For example, KD values of 7, 20, and 60 nM produced dGamma/dpi values of 14, 17, and 21 nmol m-1 mN-1, respectively. However, the trend in dGamma/dpi appears to originate from characteristics of the monolayer and not from those of the protein, since a much different adsorbate (i.e., a positively charged pyrene derivative) exhibited a similar trend in dGamma/dpi with monolayer composition. On the other hand, dGamma/dpi values of bovine prothrombin, human factor IX, human protein S, bovine protein C, and human protein C, determined using liquid-expanded phosphatidylserine monolayers, were essentially equivalent. Therefore, the five vitamin K-dependent proteins that were examined were equivalent in terms of the manner in which the gamma-carboxyglutamic acid (Gla) domain of each protein perturbed the surface pressure. This study shows that Ca2+-specific membrane contact sites in the Gla domain of the five proteins tested are similar despite the naturally occurring differences in the normal Gla domain sequence of these proteins.
authors.affiliation: Department of Chemistry and Biochemistry, University of Notre Dame, Indiana 46556, USA.
authors.forename: E H
authors.initials: EH
authors.lastname: Ellison
authors.forename: F J
authors.initials: FJ
authors.lastname: Castellino
mesh_terms: D000327:Adsorption; D000818:Animals; D001779:Blood Coagulation Factors / Q000737:chemistry*; D002135:Calcium-Binding Proteins / Q000737:chemistry; D002417:Cattle; D016326:Extracellular Matrix Proteins; D005164:Factor IX / Q000737:chemistry; D006801:Humans; D008565:Membrane Proteins / Q000737:chemistry*; D008567:Membranes, Artificial; D010713:Phosphatidylcholines; D010714:Phosphatidylethanolamines; D010718:Phosphatidylserines; D010743:Phospholipids / Q000737:chemistry*; D011312:Pressure; D011486:Protein C / Q000737:chemistry; D011516:Prothrombin / Q000737:chemistry; D013499:Surface Properties; D014812:Vitamin K / Q000097:blood*; D000097568:Matrix Gla Protein
chemical_list: D001779:Blood Coagulation Factors; D002135:Calcium-Binding Proteins; D016326:Extracellular Matrix Proteins; D005164:Factor IX; D008565:Membrane Proteins; D008567:Membranes, Artificial; D010713:Phosphatidylcholines; D010714:Phosphatidylethanolamines; D010718:Phosphatidylserines; D010743:Phospholipids; D011486:Protein C; D011516:Prothrombin; D014812:Vitamin K; D000097568:Matrix Gla Protein; C057561:1-palmitoyl-2-oleoylphosphatidylethanolamine; C050294:1-palmitoyl-2-oleoylglycero-3-phosphoserine; C028694:1-palmitoyl-2-oleoylphosphatidylcholine