Benzamidine, hydrochloride

DescriptionBenzamidine hydrochloride is a reversible inhibitor of trypsin, trypsin-like enzymes, and serine proteases. A concentration of approximately 1 mM is used for general protease inhibition. To inhibit proteases from yeast, a range of 0.5 to 4.0 mM is used and it is for the most part interchangeable with pepstatin A.In addition to being a strong competitive inhibitor of trypsin, benzamidine HCl has been also shown to be a strong competitive inhibitor of thrombin and plasmin. It was also found to be as effective as aprotinin in the prevention of glucagon degradation in human plasma.

UsesBenzamidine is a reversible inhibitor of serine proteases, including trypsin, plasmin, and thrombin (Kis = 35, 350, and 220 μM, respectively). In addition to its use as a general serine protease inhibitor, benzamidine is used, when immobilized, to purify novel proteases.

PreparationTo a stainless steel rocking autoclave equipped with a stirrer is added 103.0 gm (1.0 mole) of benzonitrile, 214.0 gm (4.0 mole) of ammonium chloride, and 306.0 gm (18.0 mole) of ammonia is introduced by means of a transfer bomb. The reaction mixture is heated at 150°C for 18 hr (pressure: 1300-6500 psig), cooled, and, with appropriate precautions for the safe control of the excess ammonia, is vented to atmospheric pressure. The reaction mixture is extracted with ether to remove approximately 5% unreacted benzonitrile, and then extracted with hot acetonitrile or ethanol to separate the amidine hydrochloride from the unreacted ammonium chloride. Concentration of the latter affords 120.5 gm (77%) of benzamidine hydrochloride, m.p. 161-163°C.