1. Kidney-cortex slices and the perfused livers of vitamin B12-deficient rats removed propionate from the incubation and perfusion media at 33 and 17% respectively of the rates found with tissues from rats receiving either a normal or a vitamin B12-supplemented diet. There was a corresponding fall in the rates of glucose synthesis from propionate in both tissues. 2. The addition of hydroxocobalamin or dimethylbenzimidazolylcobamide coenzyme to kidney-cortex slices from vitamin B12-deficient rats in vitro failed to restore the normal capacity for propionate metabolism. 3. Although the vitamin B12-deficient rat excretes measurable amounts of methylmalonate, no methylmalonate production could be detected (probably because of the low sensitivity of the method) when kidney-cortex slices or livers from deficient rats were incubated or perfused with propionate. 4. The addition of methylmalonate (5mm) to kidney-cortex slices from rats fed on a normal diet inhibited gluconeogenesis from propionate by 25%. 5. Methylmalonate formation is normally only a small fraction of the flux through methylmalonyl-CoA. This fraction increases in vitamin B12-deficient tissues (as shown by the urinary excretion of methylmalonate) presumably because the concentration of methylmalonyl-CoA rises as a result of low activity of methylmalonyl-CoA mutase (EC 5.4.99.2). Slow removal of methylmalonyl-CoA might depress propionate uptake owing to the reversibility of the steps leading to methylmalonyl-CoA formation.
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March 1970
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Research Article|
March 01 1970
Gluconeogenesis from propionate in kidney and liver of the vitamin B12-deficient rat
M. J. Weidemann;
M. J. Weidemann
1Metabolic Research Laboratory and Nuffield Department of Clinical Medicine, Radcliffe Infirmary, Oxford, U.K.
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R. Hems;
R. Hems
1Metabolic Research Laboratory and Nuffield Department of Clinical Medicine, Radcliffe Infirmary, Oxford, U.K.
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D. L. Williams;
D. L. Williams
1Metabolic Research Laboratory and Nuffield Department of Clinical Medicine, Radcliffe Infirmary, Oxford, U.K.
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G. H. Spray;
G. H. Spray
1Metabolic Research Laboratory and Nuffield Department of Clinical Medicine, Radcliffe Infirmary, Oxford, U.K.
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H. A. Krebs
H. A. Krebs
1Metabolic Research Laboratory and Nuffield Department of Clinical Medicine, Radcliffe Infirmary, Oxford, U.K.
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Publisher: Portland Press Ltd
© 1970 The Biochemical Society
1970
Biochem J (1970) 117 (1): 177–181.
Citation
M. J. Weidemann, R. Hems, D. L. Williams, G. H. Spray, H. A. Krebs; Gluconeogenesis from propionate in kidney and liver of the vitamin B12-deficient rat. Biochem J 1 March 1970; 117 (1): 177–181. doi: https://doi.org/10.1042/bj1170177
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