Conformations of trypsin-bound amidine inhibitors of blood coagulant factor Xa by double REDOR NMR and MD simulations.
Double rotational-echo double resonance (double REDOR) has been used to investigate the bound conformations of (13)C,(15)N,(19)F-labeled factor Xa inhibitors to bovine trypsin. Carbon-fluorine dipolar couplings were measured by (13)C{(19)F} REDOR with natural-abundance background interferences removed by (13)C{(15)N} REDOR. The conformations of the bound inhibitors were characterized by molecular dynamics (MD) simulations of binding restrained by double REDOR-determined intramolecular C-F distances. A symmetrical bisamidine inhibitor and an asymmetrical monoamidine-monoamine inhibitor of the same general shape had distinctly different conformations in the bound state. According to the MD models, these differences arise from specific interactions of the amidine and amine groups with the active-site residues of trypsin and nearby water molecules.
McDowell
L M
LM
Department of Chemistry, Washington University, St. Louis, Missouri 63130, USA.
McCarrick
M A
MA
Studelska
D R
DR
Guilford
W J
WJ
Arnaiz
D
D
Dallas
J L
JL
Light
D R
DR
Whitlow
M
M
Schaefer
J
J
D000818:Animals; D002417:Cattle; D015951:Factor Xa / Q000737:chemistry* / Q000378:metabolism; D008024:Ligands; D046911:Macromolecular Substances; D009682:Magnetic Resonance Spectroscopy / Q000379:methods*; D008958:Models, Molecular; D011485:Protein Binding; D011487:Protein Conformation; D013329:Structure-Activity Relationship; D014357:Trypsin / Q000378:metabolism
D008024:Ligands; D046911:Macromolecular Substances; D014357:Trypsin; D015951:Factor Xa