[Uniform method for determining the alpha 1-antitrypsin and alpha 2-macroglobulin activity in human blood serum...

A modified spectrophotometric method is developed for simultaneous estimation of alpha 1-antitrypsin and alpha 2-macroglobulin in human blood serum (plasma); the method is based on dissimilar interaction of these inhibitors with trypsin in the systems with a low molecular substrate N-alpha-benzoyl-l-arginine ethyl ester. alpha 1-Antitrypsin was estimated by inhibition of the arginine esterase activity of trypsin in a mixture containing human blood serum diluted 50-fold. alpha 2-Macroglobulin was estimated by maintained arginine esterase activity of the trypsin-alpha 2-macroglobulin complex, formed after interaction of an excess of trypsin with blood serum, diluted 10-fold and after subsequent inactivation of free, unbound with alpha 2-macroglobulin, trypsin by treatment with the soy bean inhibitor of trypsin. alpha 1-Antitrypsin and alpha 2-macrog-obulin were estimated by means of the method described in blood serum of healthy persons and in patients with burns or with carcinoma of pancreas. The method enables to estimate two main inhibitors of blood plasma proteinases in a small volume of blood serum (0.1 ml) very rapidly and specifically using commercially available substrate; the method might be recommended for routine clinical analysis.