A METHOD FOR THE DETERMINATION OF TYPE-1 IODOTHYRONINE DEIODINASE ACTIVITY IN LIVER AND KIDNEY USING I-125 LABELED REVERSE TRIIODOTHYRONINEAS A SUBSTRATE
Cs. Hotz et al., A METHOD FOR THE DETERMINATION OF TYPE-1 IODOTHYRONINE DEIODINASE ACTIVITY IN LIVER AND KIDNEY USING I-125 LABELED REVERSE TRIIODOTHYRONINEAS A SUBSTRATE, Clinical biochemistry, 29(5), 1996, pp. 451-456
Objectives: A detailed method for the determination of iodothyronine d
eiodinase type I (DI-I) activity is described. The objective of the pr
esent method development was to consolidate the effective procedures o
f previous methods and produce an efficient assay that can be easily r
eproduced. Design and methods: This method uses a 5',-I-125-labelled r
T3 as substrate and ion-exchange chromatography to separate released i
onic iodine. Released I-125- collected in the eluate is counted, and t
he results used to calculate DI-I activity. Results: Results were foun
d to be linear for tissue homogenates containing 3-11 mg protein . mL(
-1). Day-to-day coefficient of variation of liver homogenate was deter
mined to be 13%. Conclusions: This method was found to be reliable, re
producible, and sample sizes as small as 10 mu L could be readily assa
yed. The use of centrifuge filter units to contain the ion-exchange me
dium decreased handling of the material, and potential sources of erro
r.