title: Topographical relationships between the monovalent and divalent cation binding sites of des-1-41-light chain bovine plasma protein C and des-1-41-light chain-activated bovine plasma protein C.
abstract: The paramagnetic effect of Mn2+ on the longitudinal relaxation rate (T1)-1 of 205Tl+, when both cations are bound to des-1-41-light chain bovine plasma protein C (GDPC) and its activation product, des-1-41-light chain-activated bovine plasma protein C (GDAPC), has been assessed by 205Tl+ NMR spectroscopy. A substantial shortening of the T1 for Tl+ bound to either protein was observed in the presence of Mn2+, an effect not noted upon substitution of Mn2+ with the diamagnetic cation Ca2+, which is known to bind to these proteins in a similar fashion to Mn2+. This paramagnetic effect was employed to estimate distances between the monovalent and divalent cation sites in these proteins, approximately 6.7 +/- 0.2 A with GDPC and 8.3 +/- 0.2 A in GDAPC. These data suggest that a conformational alteration occurs upon activation of GDPC which leads to an increase in the distance between the monovalent and divalent cation sites.
mesh_terms: D000818:Animals; D001665:Binding Sites; D002118:Calcium / Q000378:metabolism; D002413:Cations, Divalent; D002414:Cations, Monovalent; D002417:Cattle; D004789:Enzyme Activation; D009682:Magnetic Resonance Spectroscopy; D008345:Manganese / Q000378:metabolism*; D010446:Peptide Fragments / Q000378:metabolism*; D011486:Protein C / Q000378:metabolism*; D011487:Protein Conformation; D013793:Thallium / Q000378:metabolism*
chemical_list: D002413:Cations, Divalent; D002414:Cations, Monovalent; D010446:Peptide Fragments; D011486:Protein C; C050706:protein C, des-1-41 light chain activated-; D008345:Manganese; D013793:Thallium; D002118:Calcium