title: A rapid and sensitive assay for the quantitation of carboxypeptidase N, an important regulator of inflammation.
abstract: BACKGROUND
  Carboxypeptidase N is a plasma zinc metallocarboxypeptidase which is constitutively expressed in the liver and was identified as the enzyme responsible for inactivating bradykinin and kallidin by removing the C-terminal arginine. Because CPN can cleave the C-terminal arginine of C3a, C4a and C5a it is often referred to as anaphylatoxin inactivator. Markedly reduced levels of circulating CPN are associated with recurrent angioedema and abnormal cutaneous polymorphonuclear cell infiltration.
  
  
  METHODS
  In this paper we describe a fast kinetic coupled enzymatic assay for the sensitive measurement of carboxypeptidase N activities in serum samples. The assay makes use of the excellent CPN substrate Benzoyl-L-Alanyl-L-Arginine.
  
  
  RESULTS
  This novel assay is very fast, easy to perform and combines good reliability and reproducibility with excellent correlation with the HPLC-assisted assay (r=0.927; n=140).
  
  
  CONCLUSIONS
  The presented assay can be used for high throughput screening of this important regulator of inflammation in clinical plasma or serum samples.
authors.affiliation: Laboratory of Medical Biochemistry, University of Antwerp, Universiteitsplein 1, 2610 Wilrijk, Antwerp, Belgium.
authors.forename: Johan L
authors.initials: JL
authors.lastname: Willemse
authors.forename: Dirk F
authors.initials: DF
authors.lastname: Hendriks
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D000706:Anaphylatoxins / Q000037:antagonists & inhibitors / Q000378:metabolism; D001681:Biological Assay; D002851:Chromatography, High Pressure Liquid; D004151:Dipeptides / Q000378:metabolism; D006801:Humans; D007249:Inflammation / Q000097:blood* / Q000473:pathology; D007700:Kinetics; D001121:Lysine Carboxypeptidase / Q000097:blood*; D008875:Middle Aged; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity
chemical_list: D000706:Anaphylatoxins; D004151:Dipeptides; C021964:benzoylalanylarginine; D001121:Lysine Carboxypeptidase