title: A serum enzyme test to detect pulmonary capillary injury.
abstract: Lung converting enzyme (LCE) was extracted from normal human lung obtained at autopsy. The specificity of the enzyme preparation was confirmed in vitro by incubation with Angiotensin I (AI) and paper chromatographic identification of reaction products. A method was developed for assay of the enzyme preparation in human serum using tritiated Angiotensin I (H-3A-I) as substrate. Enzyme activity is quantitated by scintillation counting the radioactive end product tritiated dipeptide histadylleucine (H-3His-leu). Serum from the authors and pooled serum from the hospital laboratory caused less than 3.5% conversion of H-3A-I to H-3His-leu. Serum from two patients with severe lung damage caused a maximum 20% conversion of H-3A-I to H-3His-leu. Percent conversion in these patients correlated with clinical and laboratory evidence of lung dysfunction.
mesh_terms: D000804:Angiotensin II / Q000096:biosynthesis; D002196:Capillaries; D002268:Carboxypeptidases / Q000097:blood* / Q000302:isolation & purification; D002854:Chromatography, Paper; D004796:Clinical Enzyme Tests; D004151:Dipeptides / Q000378:metabolism; D006639:Histidine; D006801:Humans; D007930:Leucine / Q000378:metabolism; D008168:Lung / Q000098:blood supply* / Q000201:enzymology; D008171:Lung Diseases / Q000175:diagnosis*; D001121:Lysine Carboxypeptidase / Q000097:blood*; D008297:Male; D008875:Middle Aged; D014316:Tritium
chemical_list: D004151:Dipeptides; D014316:Tritium; D000804:Angiotensin II; D006639:Histidine; D002268:Carboxypeptidases; D001121:Lysine Carboxypeptidase; D007930:Leucine