Half-Lives of the Same Enzymes in Different Tissues

Half-Lives of the Same Enzymes in Different Tissues 

There are several examples where half-lives for the same enzyme show wide variations between tissues. Thus phosphoenolpyruvate car-boxykinase, which has a half life of about 6 h in rat liver and in cultured hepatoma cells, has a half-life of 20 h or more in adipose tissue and kidney (Hopgood et al., 1973 lynedjian et al., 1975). Also, lactate dehydrogenase isoenzyme 5 has been reported to have half-lives of 1.6, 16, and 31 days in heart, liver, and skeletal muscle, respectively (Fritz et al., 1969), while the half-life of ornithine aminotransferase is 1 day in liver and 3.5 days in the Morris hepatoma 44 (Kobayashi et al., 1976). 

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