Effect of diet composition on coenzyme A and its thioester pools in various rat tissues.

Three coenzyme A (CoA) molecular species, i.e., acetyl-CoA, malonyl-CoA, and nonesterified CoA (CoASH), in 13 types of fasted rat tissue were analyzed. A relatively larger pool size of total CoA, consisting of acetyl-CoA, malonyl-CoA, and CoASH, was observed in the medulla oblongata, liver, heart, and brown adipose tissue. Focusing on changes in the CoA pool size in response to the nutrient composition of the diet given, total CoA pools in rats continuously fed a high-fat diet for 4 weeks were significantly higher in the hypothalamus, cerebellum, and kidney, and significantly lower in the liver and skeletal muscle than those of rats fed a high-carbohydrate or high-protein diet. In particular, reductions in the liver were remarkable and were caused by decreased CoASH levels. Consequently, the total CoA pool size was reduced by approximately one-fifth of the hepatic contents of rats fed the other diets. In the hypothalamus, which monitors energy balance, all three CoA molecular species measured were at higher levels when rats were fed the high-fat diet. Thus, it was of interest that feeding rats a high-fat diet affected the behaviors of CoA pools in the hypothalamus, liver, and skeletal muscle, suggesting a significant relationship between CoA pools, especially malonyl-CoA and/or CoASH pools, and lipid metabolism in vivo.

Coenzyme A and its thioester pools in fasted and fed rat tissues.

Levels of three coenzyme A (CoA) molecular species, i.e., nonesterified CoA (CoASH), acetyl-CoA, and malonyl-CoA, in fasted and fed rat tissues were analyzed by the acyl-CoA cycling method which makes detection possible at the pmol level. Malonyl-CoA in brain tissues readily increased with feeding, and inversely, acetyl-CoA decreased. This phenomenon occurred in the cerebral cortex, hippocampus, cerebellum, and medulla oblongata, as well as in the hypothalamus which controls energy balance by monitoring malonyl-CoA. In the non-brain tissues, the sizes of the acetyl-CoA, malonyl-CoA, and CoASH pools depended on the tissues. The total CoA pools consisting of the above three CoA species in the liver, heart, and brown adipose tissue were larger and those of the perirenal, epididymal, and ovarian adipose tissues were much smaller, compared with those of other tissues including brain tissues. In addition, the response of each CoA pool to feeding was not uniform, suggesting that the tissue-specific metabolism individually functions in the non-brain tissues. Thus, a comprehensive analysis of thirteen types of rat tissue revealed that CoA pools have different sizes and showed a different response to fasting and feeding depending on the tissue.

Biochemical characterization of cellulose-binding proteins (CBPA and CBPB) from the rumen cellulolytic bacterium Eubacterium cellulosolvens 5.

The cellulose-binding proteins, CBPA and CBPB, of rumen cellulolytic bacterium Eubacterium cellulosolvens 5 were biochemically characterized, and their properties were compared. Recombinant CBPA and CBPB were a typical 1,4-beta-endoglucanase. Both proteins bound to insoluble polysaccharides such as Avicel cellulose, acid swollen cellulose, lichenan, chitin, and oat spelt xylan. On the other hand, only recombinant CBPB bound to agarose and starch.