Traceability of values for catalytic activity concentration of enzymes: a Certified Reference Material for aspartate transaminase.
BACKGROUND
A new reference material for the liver enzyme aspartate transaminase (AST) (L-aspartate: 2-oxoglutarate-aminotransferase, EC 2.6.1.1), also called aspartate aminotransferase (ASAT), has been developed under the code ERM-AD457/IFCC. This certified reference material (CRM) for AST has been produced from a human type recombinant AST expressed in Escherichia coli and a buffer containing bovine serum albumin, and has been lyophilised.


METHODS
The homogeneity and the stability of the material have been tested and the catalytic activity concentration has been characterised by 12 laboratories using the reference procedure for AST at 37 degrees C from the International Federation of Clinical Chemistry and Laboratory Medicine (IFCC).


RESULTS
The certified catalytic activity concentration and certified uncertainty of AST in the reconstituted material are (1.74+/-0.05) microkat/L or (104.6+/-2.7) U/L (with a coverage factor k=2; 95% confidence interval).


CONCLUSIONS
Both the certified value and uncertainty are traceable to the International System of Units (SI). The material is aiming to control the IFCC reference procedure for AST at 37 degrees C, which will then be used to assign values to calibrants and control materials. The present paper highlights the scientific challenges and innovations which were encountered during the development of this new CRM.
Toussaint
Brigitte
B
Institute for Reference Materials and Measurements (IRMM), Joint Research Centre, European Commission, Geel, Belgium. Brigitte.Toussaint@ec.europa.eu
Emons
Hendrik
H
Schimmel
Heinz G
HG
Bossert-Reuther
Steffen
S
Canalias
Francesca
F
Ceriotti
Ferruccio
F
Férard
Georges
G
Ferrero
Carlo A
CA
Franck
Paul F H
PF
Gella
F Javier
FJ
Henny
Joseph
J
Jørgensen
Poul J
PJ
Klauke
Rainer
R
Lessinger
Jean-Marc
JM
Mazziotta
Daniel
D
Panteghini
Mauro
M
Ueda
Shigeru
S
Schumann
Gerhard
G
D000818:Animals; D001219:Aspartate Aminotransferases / Q000032:analysis / Q000235:genetics / Q000592:standards*; D002417:Cattle; D004796:Clinical Enzyme Tests / Q000379:methods / Q000592:standards*; D006801:Humans; D011994:Recombinant Proteins / Q000032:analysis / Q000235:genetics / Q000592:standards; D012015:Reference Standards; D012710:Serum Albumin, Bovine / Q000737:chemistry; D035501:Uncertainty
D011994:Recombinant Proteins; D012710:Serum Albumin, Bovine; D001219:Aspartate Aminotransferases