Displacement of thiamine pyrophosphate from swollen mitochondria

Abstract

The distribution of TPP in cytoplasm fractions of rat liver is studied. When the homogenate was prepared with 0.25M sucrose, about 300% of TPP was present in mitochondria. When the homogenization medium was distilled water, the amount of TPP present in this fraction was markedly decreased, while that present in the supernatant fluid was increased. Mitochondria suspended in 0.25M sucrose and incubated at 18° C for 10 min release in the suspension fluid about 20% of their TPP; under the same conditions, mitochondria suspended in water release about 65% of their TPP. An increased destruction of TPP was observed as a result of incubation of mitochondria in water at 18° C.

The distribution of TPP in fatty liver homogenates prepared in 0.25M sucrose resembles strongly that observed for homogenates of normal rat liver prepared in distilled water; TPP was decreased in the mitochondrial fraction and correspondingly increased in the supernatant. Total TPP is decreased in fatty liver obtained by feeding rats on a diet deficient in choline. It remains practically unchanged in fatty liver produced by CCl4.