Rapid screening for deficiency of alpha 1-proteinase inhibitor.

Abstract

This rapid screening procedure for detection of low but functional elastase-inhibitory activity in human plasma is based on the fact that incubation of excess porcine pancreatic elastase (EC 3.4.21.36) with plasma results in formation of a complex with active alpha 1-proteinase inhibitor (alpha 1PI, also called alpha 1-antitrypsin). In normal individuals all of the elastase is complexed, leaving no free enzyme to hydrolyze the elastase substrate, and the reaction mixture remains clear. Because individuals homozygous for the Z allele have relatively low concentrations of alpha 1PI, their plasma cannot complex all of the elastase in the assay. The uncomplexed enzyme hydrolyzes the elastase-specific p-nitroanilide substrate, producing a yellow reaction mixture. Use of this simple assay for early screening of individuals for alpha 1PI deficiency may substantially decrease the number of untreated cases of familial emphysema, a disorder that develops as a result of a genetically derived proteinase-proteinase inhibitor imbalance.

Temporal changes in factors associated with neutrophil elastase and coagulation in intensive care patients with a biphasic waveform and disseminated intravascular coagulation

“…A1PI activity assay The ability of increasing volumes of normal human pooled plasma and patient plasma to inhibit a fixed amount of exogenously added porcine elastase was measured using a modification of the method of Lloyd and Travis [53]. Briefly, plasma (30 µL) was first treated with 0.2 m methylamine for 15 min at room temperature to inactivate the Α2M.…”