Description
Benzamidine 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.
Chemical Properties
white to off-white powder
Uses
Benzamidine 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.
Preparation
To 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.
Biological Activity
Benzamidine hydrochloride is an reversible competitive inhibitor of trypsin-like serine proteases, with Kis of 97 μM, 21 μM, 20 μM and 110 μM for uPA, trypsin, tryptase and factor Xa, respectively.
Safety Profile
Moderately toxic byintraperitoneal route. When heated to decomposition itemits toxic vapors of NOx, HCl, and Cl
-.
in vitro
Benzamidine hydrochloride has weak inhibition for tPA and thrombin, with Kis of 750 μM and 320 μM, respectively.
References
1) Markwardt?et al. (1968)?Comparative studies on the inhibition of trypsin, plasmin, and thrombin by derivatives of benzylamine and benzamide; Eur. J. Biochem.,?6?502
2) Deutscher?et al.?(1990),?Maintaining protein stability; Methods Enzymol.,?182?83
3) Jaswinski?et al.?(1990),?Preparations of extracts from yeast; Methods Enzymol.,?182?154
4) Ensinck?et al.?(1972),?Use of Benzamidine as a proteolytic inhibitor in the radioimmunoassay of glucagon in plasma; J. Clin. Endocrinol. Metab.,?35?463
5) Jeffcoate?et al. (1974),?Use of benzamidine to prevent the destruction of thyrotropin-releasing hormone (TRH) by blood; Endocrinol. Metab,?38?155
