Factor Xa in complex with the inhibitor 1-[6-methyl-4,5,6,7-tetrahydrothiazolo(5,4-c)pyridin-2-yl] carbonyl-2-carbamoyl-4-(6-chloronaphth-2-ylsulphonyl)piperazine
Synthesis and conformational analysis of a non-amidine factor Xa inhibitor that incorporates 5-methyl-4,5,6,7-tetrahydrothiazolo[5,4-c]pyridine as S4 binding element
Our exploratory study was based on the concept that a non-amidine factor Xa (fXa) inhibitor is suitable for an orally available anticoagulant. We synthesized and evaluated a series of N-(6-chloronaphthalen-2-yl)sulfonylpiperazine derivatives incorporatin ...
Our exploratory study was based on the concept that a non-amidine factor Xa (fXa) inhibitor is suitable for an orally available anticoagulant. We synthesized and evaluated a series of N-(6-chloronaphthalen-2-yl)sulfonylpiperazine derivatives incorporating various fused-bicyclic rings containing an aliphatic amine expected to be S4 binding element. Among this series, 5-methyl-4,5,6,7-tetrahydrothiazolo[5,4-c]pyridine type 61 displayed orally potent anti-fXa activity and evident prolongation of prothrombin time (PT) with the moderate bioavailability in rats. The X-ray crystal analysis afforded an obvious binding mode that 5-methyl-4,5,6,7-tetrahydrothiazolo[5,4-c]pyridine and 6-chloronaphthalene respectively bound to S4 and S1 subsites. In this X-ray study, we discovered a novel intramolecular S-O close contact. Ab initio energy calculations of model compounds deduced that conformers with the most close S-O proximity were most stable. The Mulliken population analysis proposed that this energy profile was caused by both of electrostatic S-O affinity and N-O repulsion. The results of these calculations and X-ray analysis suggested a possibility that the restricted conformation effected the affinity to S4 subsite of fXa.
Related Citations:
Structural basis for chemical inhibition of human blood coagulation factor Xa Kamata, K., Kawamoto, H., Honma, T., Iwama, T., Kim, S.H. (1998) Proc Natl Acad Sci U S A 95: 6630
X-ray structure of active site-inhibited clotting factor Xa. Implications for drug design and substrate recognition Brandstetter, H., Kuhne, A., Bode, W., Huber, R., von der Saal, W., Wirthensohn, K., Engh, R.A. (1996) J Biol Chem 271: 29988
Structure of human des(1-45) factor Xa at 2.2 A resolution Padmanabhan, K., Padmanabhan, K.P., Tulinsky, A., Park, C.H., Bode, W., Huber, R., Blankenship, D.T., Cardin, A.D., Kisiel, W. (1993) J Mol Biol 232: 947
Organizational Affiliation:
Medicinal Chemistry Research Laboratory, Discovery Research Laboratory, Drug Metabolism & Physicochemical Property Research Laboratory, Daiichi Pharmaceutical Co. Ltd, 1-16-13, Kita-Kasai, Edogawa-ku, Tokyo 134-8630, Japan. hagin9kg@daiichipharm.co.jp
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