Amidino-substituted aromatic heterocycles as probes of the specificity pocket of trypsin-like proteases.
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Acrosin↗
Biomedical subjects
J D Geratz
Publications and source records attributed to J D Geratz.
Specific inhibition of platelet agglutination and aggregation by aromatic amidino compounds.
A series of aromatic amidino compounds were investigated for their inhibitory effect on platelet agglutination and platelet aggregation. Agglutination of fresh or fixed platelets was produced by bovine plasma or by human plasma in combination with ristocetin, while aggregation of fresh platelets was induced by ADP, thrombin or collagen. Highly effective inhibitors were found for both types of platelet clumping, but there was no parralelism between the inhibitory activities in the two test system. 5-(5-amidino-2-benzimidazolyl)-2-(4-hydroxybenzene)benzimidazole suppressed agglutination exclusively. Pentamidine, on the other hand, strongly blocked the aggregation reaction, but did not interfere with agglutination, even at high concentrations. Compounds which inhibited aggregation also prevented the liberation of serotonin from the platelets.
Adenosine Diphosphate↗
Diarylamidine derivatives with one or both of the aryl moieties consisting of an indole or indole-like ring. Inhibitors of arginine-specific esteroproteases.
A series of 62 diarylamidine derivatives was evaluated for their antiproteolytic activity. In all but two of the compounds one or both of the amidino-substituted aryl moieties was either an indole or an indole-like ring. The latter included indene, benzimidazole, benzofuran, benzol[beta]thiophene, and several other related nitrogen-containing heterocycles. Several of the compounds exhibited considerable inhibitory potency against thrombin, trypsin, and pancreatic kallikrein. An outstanding inhibitor of trypsin was found in bis(5-amidino-2-benzimidazolyl)methane (compound 42) with a Ki value of 1.7 X 10(-8) M(pH. 8.1, 37 degrees C). Another derivative, 1,2-di(4-amidino-2-benzofuranyl)ethane (compound 21), proved to be a highly effective inhibitor of the overall blood clotting process. From a general structure-activity standpoint these compounds demonstrate that minor structural variations of low-molecular-weight inhibitors can result in significant changes in specificity and potency with regard to antiproteolytic activity.
Amidines↗
Structure-activity relationships for the inhibition of acrosin by benzamidine derivatives.
A series, consisting of 52 benzamidine derivatives, was evaluated for inhibitory activity against homogeneous boar sperm acrosin. All of the compounds in the series proved to be more potent than benzamidine (Ki = 4.0 x 10(-6) M), with one of the derivatives, alpha-(4-amidino-2,6-diiodophenoxy)-3-nitrotoluene (compound 16), showing outstanding potency with a Ki value of 4.5 X 10(-8) M. Although all of the derivatives were effective acrosin inhibitors, structural specificity was observed within homologous groups of compounds. The information gained from this preliminary study should prove extremely beneficial in the design and synthesis of future acrosin inhibitors.
Acrosin↗
Current concepts on action of synthetic thrombin inhibitors.
The development of synthetic inhibitors of thrombin and of related arginine-specific esteroproteases is reviewed. The superiority of bis- and tris-benzamidines over benzamidine is disccussed and related to the presence on the enzyme of secondary binding sites beyond the specificity pocket. It is demonstrated that inhibitors with marked specificity for a single enzyme can be produced, and with the help of such selective compounds it is shown that inhibition of factor Xa is more significant for overall anticoagulant effect than inhibition of thrombin.
Antithrombins↗