title: A sensitive ELISA for serum ornithine carbamoyltransferase utilizing the enhancement of immunoreactivity at alkaline pH.
abstract: BACKGROUND
  We developed a new enzyme-linked immunosorbent assay (ELISA) for ornithine carbamoyltransferase (OCT) and evaluated its usefulness.
  
  
  METHODS
  Recombinant human OCT expressed in E. coli was used as an antigen to obtain the monoclonal antibodies for this assay.
  
  
  RESULTS
  The reactivity of the antibodies to native OCT as well as recombinant OCT was enhanced at alkaline pH (8.5-10), and the assay's sensitivity was markedly improved. The antibodies react identically with native and recombinant OCT at pH 9.4. The dilution test showed a good linearity between dilution ratios and the concentrations. Different concentrations of OCT added were recovered on average at 90.4%. There was a good correlation between OCT protein levels in the ELISA and OCT enzyme activities (r=0.987, p<0.0001). A significant difference in the serum level of OCT was observed between chronic hepatitis patients (110.7+/-80 ng/ml) and healthy subjects (34.4+/-20.7 ng/ml) (p<0.0001). The serum levels of OCT between sexes differed significantly in the healthy subjects (p<0.0001).
  
  
  CONCLUSIONS
  Our newly established ELISA for OCT using monoclonal antibodies is sensitive enough for clinical application.
authors.affiliation: Immunology Laboratory, Diagnostics Department, YAMASA Corporation, 2-10-1 Araoi-cho, Choshi, Chiba, 288-0056, Japan. murayama@yamasa.com
authors.forename: Hiroshi
authors.initials: H
authors.lastname: Murayama
authors.forename: Makoto
authors.initials: M
authors.lastname: Igarashi
authors.forename: Masataka
authors.initials: M
authors.lastname: Mori
authors.forename: Yoshihiro
authors.initials: Y
authors.lastname: Fukuda
authors.forename: Masaki
authors.initials: M
authors.lastname: Ikemoto
authors.forename: Atsuo
authors.initials: A
authors.lastname: Nagata
mesh_terms: D000410:Alanine Transaminase / Q000097:blood; D000468:Alkalies; D002850:Chromatography, Gel; D004797:Enzyme-Linked Immunosorbent Assay / Q000379:methods*; D015870:Gene Expression; D006262:Health; D006521:Hepatitis, Chronic / Q000097:blood; D006801:Humans; D006863:Hydrogen-Ion Concentration; D009954:Ornithine Carbamoyltransferase / Q000097:blood* / Q000235:genetics / Q000276:immunology* / Q000302:isolation & purification; D012680:Sensitivity and Specificity
chemical_list: D000468:Alkalies; D009954:Ornithine Carbamoyltransferase; D000410:Alanine Transaminase