title: An amidolytic assay for determination of alpha 1-antitrypsin in serum and in cerebrospinal fluid.
abstract: An amidolytic assay using the chromogenic substrate tosyl-glycyl-prolyl-lysine-4-nitranilide acetate (Chromozym PL) has been studied for the determination of alpha 1-antitrypsin in serum and in cerebrospinal fluid (CSF). It was found that binding of trypsin to alpha 2-macroglobulin has to be taken into consideration when alpha 1-antitrypsin is determined by an amidolytic assay. In serum this accounts for 7.4 +/- 3.2% and in CSF 2.8 +/- 1.8% of the total antitrypsin capacity. The reference range of alpha 1-antitrypsin in sera was found to be x = 60.3 +/- 20.8 kIU/l, and in CSF mean = 186 +/- 99 IU/l. Within-run precision showed a C.V. of 1.36% in sera, and a C.V. of 1.86% in CSF. There was a good correlation with immunochemical methods: r = 0.946 in 65 sera (p less than 0.001) and r = 0.986 in 55 samples of CSF (p less than 0.001).
mesh_terms: D002863:Chromogenic Compounds; D006801:Humans; D005779:Immunodiffusion; D007700:Kinetics; D008722:Methods; D009842:Oligopeptides; D012016:Reference Values; D014357:Trypsin; D000515:alpha 1-Antitrypsin / Q000032:analysis* / Q000134:cerebrospinal fluid; D000511:alpha-Macroglobulins
chemical_list: D002863:Chromogenic Compounds; D009842:Oligopeptides; D000515:alpha 1-Antitrypsin; D000511:alpha-Macroglobulins; C034172:chromozym PL; D014357:Trypsin