Determination of the Catalytic Activity
Concentration in Serum of Gamma–
glutamyltransferase (EC
2.3.2.2,
GT)
BASED ON THE PROVISIONAL IFCC REFERENCE METHOD (l)
AND ON THE NORDIC RECOMMENDED ( SCE) METHOD
This ECCLS standard is based on the corresponding IFCC Refe–
rence Method for determination of GT, which has been adapted
by this ECCLS Subcommittee for routine use in European clini–
cal chemistry laboratories. For reasons given below, an al–
ternative (SCE) procedure using the non-patented substrate
gamma-glutamyl-4-nitroanilide with calibration is also
described.
This standard recommends reaction conditions and describes
the tolerance limits for variations in measurement that ne–
vertheless allow routine determinations of the catalytic con–
centration of GT to be equivalent to those of the unmodified
IFCC GT Reference Method.
For details not given in this standard refer to the original
IFCC document, GT (Part 4, Stage 2, Draft 2, Provisional re–
commendation 1983) of the IFCC Reference Methods for measure–
ment of catalytic concentration of enzymes (l).
Patented and alternative donor substrates.
A particular problem for GT, however, is that the donor sub–
strate, gamma-glutamyl-3-carboxy-4-nitroanilide (Glucana), in
the IFCC GT Reference Method is patent-protacted, and licen–
ses for productian of reagent kits , for routine use are not at
present universally available throughout Europe. For this
reason, an alternative method employing the less-soluble
non-carboxylated substrate is also presented as an acceptable
Klinisk kemi i Norden 2: suppl, 1990
75
