Assay of Procarboxypeptidase U, a Novel Determinant of the Fibrinolytic Cascade, in Human Plasma

Procarboxypeptidase U (proCPU) is a novel proenzyme found in human plasma. The active form, carboxypeptidase U (CPU; EC 3.4.17.20), retards the rate of fibrinolysis through its ability to cleave C-terminal lysine residues on fibrin partially degraded by plasmin. This reduces the number of high-affin...

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Bibliographic Details
Published in:Clinical chemistry (Baltimore, Md.) Md.), 1999-06, Vol.45 (6), p.807-813
Main Authors: Schatteman, Katinka A, Goossens, Filip J, Scharpe, Simon S, Neels, Hugo M, Hendriks, Dirk F
Format: Article
Language:English
Subjects:
Adult
Aged
Biological and medical sciences
Blood coagulation
Carboxypeptidase B2
Carboxypeptidases - blood
Chromatography, High Pressure Liquid
Enzyme Activation
Female
Fibrinolysis
Humans
Investigative techniques, diagnostic techniques (general aspects)
Male
Medical sciences
Middle Aged
Reference Values
Reproducibility of Results
Sensitivity and Specificity
Thrombin
Thrombomodulin
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Summary:Procarboxypeptidase U (proCPU) is a novel proenzyme found in human plasma. The active form, carboxypeptidase U (CPU; EC 3.4.17.20), retards the rate of fibrinolysis through its ability to cleave C-terminal lysine residues on fibrin partially degraded by plasmin. This reduces the number of high-affinity plasminogen-binding sites on fibrin. We developed an assay to determine the proCPU concentration in human plasma. The assay involved quantitative conversion of proCPU to active CPU by thrombin-thrombomodulin, a very efficient activator of proCPU, followed by determination of the enzymatic activity of CPU with the substrate hippuryl-L-arginine, using an HPLC-assisted determination of the released hippuric acid. Using this method, we established a reference interval based on 490 healthy individuals. The mean proCPU concentration, determined after activation of the zymogen in diluted plasma and expressed as CPU activity, was 964 U/L, with a SD of 155 U/L. The population showed a gaussian distribution. However, we noticed important differences related to age and the use of hormone preparations. The sensitivity and precision of the method make it suitable for routine clinical determinations and as a reference procedure.
ISSN:0009-9147
1530-8561
DOI:10.1093/clinchem/45.6.807