Transketolase, pyruvate and oxoglutarate dehydrogenase activities and [14C]thiamin turnover in tissues of mice fed thiamin-deficient diet.
A study was made of turnover of [14C]thiamin (5 or 2 micrograms/mouse) in mice fed a thiamin-deficient diet. Simultaneously the activities of the thiamin-dependent enzymes (transketolase, pyruvate and oxoglutarate dehydrogenases) were measured as an index of efficiency of fulfilling the coenzyme function of the vitamin under conditions of different thiamin status. After [14C]thiamin injections of 5 micrograms/mouse, kidney, spleen, stomach and pancreas tissue stores turned over completely on day 9, whereas by day 13 this process had not yet been finished in liver, heart and brain. On administration of 2 micrograms [14C]thiamin/mouse, turnover of the tissue stores proceeded at a slower rate. The tissue transketolase activity decreased after the 2-microgram injections as compared to that in the mice administered 5-microgram injections. With 2 micrograms of [14C]thiamin, the pyruvate dehydrogenase activity lowered gradually in all the tissues studied, whereas the oxoglutarate dehydrogenase decreased in liver and kidneys. The pattern of the depression of the thiamin-dependent enzyme activities after the 2-microgram [14C]thiamin injections suggests a regularity in the vitamin redistribution in different organs and subcellular fractions.
D000818:Animals; D004032:Diet; D005260:Female; D007655:Ketoglutarate Dehydrogenase Complex / Q000378:metabolism*; D007658:Ketone Oxidoreductases / Q000378:metabolism*; D007700:Kinetics; D051379:Mice; D030481:Pyruvate Dehydrogenase (Lipoamide); D011768:Pyruvate Dehydrogenase Complex / Q000378:metabolism*; D013831:Thiamine / Q000378:metabolism*; D013832:Thiamine Deficiency / Q000201:enzymology / Q000378:metabolism*; D014174:Transketolase / Q000378:metabolism*
D011768:Pyruvate Dehydrogenase Complex; D007658:Ketone Oxidoreductases; D030481:Pyruvate Dehydrogenase (Lipoamide); D007655:Ketoglutarate Dehydrogenase Complex; D014174:Transketolase; D013831:Thiamine