1.1 ECCLS Measurement Procedure:
o
o
Substrate start, 37 C and 30
c.
The component concentrations in the final reaction mixture
are the same as those of the IFCC CK Reference Method.
o
reaction system performs equally
we~l
at 37.0 C and 30.0
The standard reaction conditions have been defined at 37
in Table l below.
The
o
c.
o
c
The imidazole buffer has a temperature dependence similar to
that of the catalytic activity of the human CK isoenzymes MM,
MB,
and
BB
(Sb, 18). Consequently, the same reaction system,
o
adjusted to a pH of 6.60 at 30 C will change to a pH of 6.5
o
0.02 at 37
C supporting the reaction equally well at both
temperatures (18).
The standard procedure invalves two stages (Table l). In
t~e
first, the sample is incubated with the reagent mixture with–
out creatine phosphate (reagent A). CK molecules are activa–
ted during this phase. The catalyzed reaction is initiated by
addition of creatine phosphate (reagent B).
The catalytic activity concentrations of the auxiliary enzy–
mes are determined as described in the IFCC Reference CK Me-
o
o
thod at 30 C and 37
c.
The average temperature conversion
o
o
factors 37 C/ 30 C were found to be 1.30 for Hexokinase and
1.40 for Glucose-6-P-dehydrogenase (G-6-PDH) (19 a,b).
o
The values in Table l earrespond to those obtained at 37
c.
It should be noted that most commercial reagents contain ex–
cess amounts of enzymes to ensure a realistic shelf-life.
Klinisk kemi
i
Norden 2: suppl. 1990
19
