The determination of a calcium-dependent binding constant of the bovine prothrombin Gla domain (residues 1-45) to phospholipid vesicles.
Calcium-mediated binding of the radioiodinated peptide representing residues 1-45 of bovine prothrombin to single bilayer phospholipid vesicles composed of phosphatidylserine from bovine brain and synthetic 1-palmitoyl-2-oleoyl-phosphatidylcholine (25:75 PS/PC) has been studied over peptide concentrations from 0.33 microM to 3.75 microM and at a calcium concentration of 1.0 mM. The binding isotherm for the interaction between the radioiodinated peptide and PS/PC vesicles fits a model in which there is noncooperative binding of the peptide to non-interacting sites on the phospholipid bilayer. A dissociation constant determined at these conditions is 11.8 microM compared to 1.0 microM for prothrombin fragment 1.
Department of Chemistry, University of North Carolina, Chapel Hill 27599-3290.
D J
DJ
Weber
J S
JS
Pollock
L G
LG
Pedersen
R G
RG
Hiskey
D015055:1-Carboxyglutamic Acid / Q000378:metabolism*; D000818:Animals; D002118:Calcium / Q000502:physiology*; D002417:Cattle; D007700:Kinetics; D008081:Liposomes; D046911:Macromolecular Substances; D010446:Peptide Fragments / Q000378:metabolism; D011485:Protein Binding; D011498:Protein Precursors / Q000378:metabolism; D011516:Prothrombin / Q000378:metabolism*; D013329:Structure-Activity Relationship; D013816:Thermodynamics
D008081:Liposomes; D046911:Macromolecular Substances; D010446:Peptide Fragments; D011498:Protein Precursors; D015055:1-Carboxyglutamic Acid; C029733:prothrombin fragment 1; D011516:Prothrombin; D002118:Calcium