Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: EC:3.4.21.6 (thromboplastin)
 13,278 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

A series of new compounds, 6-amino-1-naphthalenesulfonamides (ANSN), were used as fluorescent detecting groups for substrates of amidases. These compounds have a high quantum fluorescent yield, and the sulfonyl moiety permits a large range of chemical modification. Fifteen ANSN substrates with the structure (N alpha-Z)Arg-ANSNR1R2 were synthesized and evaluated for their reactivity with 8 proteases involved in blood coagulation and fibrinolysis. Thrombin, activated protein C, and urokinase rapidly hydrolyzed substrates with monosubstituted sulfonamide moieties (R1 = H). The maximum rate of substrate homologue). The hydrolysis rates for substrates with branched substituents were slower than their linear analogues. Monosubstituted (N alpha-Z)Arg-ANSNR1R2 possessing cyclohexyl or benzyl groups in the sulfonamide moiety were hydrolyzed by these three enzymes at rates similar to that of the n-butyl homologue (except the cyclohexyl compound for u-PA). Factor Xa rapidly hydrolyzed substrates with short alkyl chains, especially when R1 = R2 = CH3 or C2H5. Lys-plasmin and rt-PA demonstrated low activity with these compounds, and the best results were accomplished for monosubstituted compounds when R2 = benzyl (for both enzymes). Factor VIIa and factor IXa beta exhibited no activity with these substrates. A series of 14 peptidyl ANSN substrates were synthesized, and their reactivity for the same 8 enzymes was evaluated. Thrombin, factor Xa, APC, and Lys-plasmin hydrolyzed all of the substrates investigated. Urokinase, rt-PA, and factor IXa beta exhibited reactivity with a more limited group of substrates, and factor VIIa hydrolyzed only one compound (MesD-LGR-ANSN(C2H5)2). The substrate ZGGRR-ANSNH (cyclo-C6H11) showed considerable specificity for APC in comparison with other enzymes (kcat/KM = 19,300 M-1 s-1 for APC, 1560 for factor IIa, and 180 for factor Xa). This kinetic advantage in substrate hydrolysis was utilized to evaluate the activation of protein C by thrombin in a continuous assay format. Substrate (D-LPR-ANSNHC3H7) was used to evaluate factor IX activation by the factor VIIa/tissue factor enzymatic complex in a discontinuous assay. A comparison between the commercially available substrate chromozyme TH (p-nitroanilide) and the ANSN substrate with the same peptide sequence (TosGPR) demonstrated that aminonaphthalenesulfonamide increased the specificity (kcat/KM) of substrate hydrolysis by thrombin more than 30 times, with respect to factor Xa substrate hydrolysis.
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PMID:Aminonaphthalenesulfonamides, a new class of modifiable fluorescent detecting groups and their use in substrates for serine protease enzymes. 160 66

The antihypertensive drug, captopril, exerted an anticoagulant effect upon clotting time as followed by prothrombin time (PT) and activated partial thromboplastin time (APTT), with prolongation of clotting observed at 4.25 x 10(-3) M and 4 x 10(-3) M captopril for PT and APTT, respectively, using commercial level I plasma. Utilizing level III plasmas, PT and APTT values were both prolonged by 4.25 x 10(-3) M captopril. Captopril (6 x 10(-3) M) also directly prolonged the clotting of thrombin in a thrombin-factor II-deficient plasma assay, whereas 5 x 10(-3) M captopril inhibited FIIDP in a thrombin-FIIDP assay. In thrombin-fibrinogen assays, pre-incubation of 2.5 x 10(-3) M captopril with fibrinogen also prolonged clotting time, whereas 3 x 10(-3) M captopril prolonged thrombin activity. These data suggest that thiol-disulfide exchange permits reduction of disulfide groups in thrombin and fibrinogen, altering their tertiary structure and physiological function. Lisinopril at a pharmacological 10(-2) M also prolonged APTT, although it lacks a thiol group. Polylysine (1k-4k) affected a prolongation of APTT at 6.7 x 10(-6) M, suggesting inhibition of clotting by a different mechanism.
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PMID:Anticoagulant activity of captopril. 1820 75