Synthesis of Co-methyl cobalamin by cell-free extracts of Clostridium thermoaceticum

Kuratomi, Kazuoki; Poston, J. Michael; Stadtman, Earl R.

doi:10.1016/0006-291x(66)90455-4

Cited by 13 publications

(4 citation statements)

References 9 publications

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“…From evidence with intact C. thermoaceticum the methyl-factor Illm formed from 1 4C02 is about ten-fold more radioactive than HC-methylcobalamin re covered from added methylcobalamin (177 ). Experiments with cell-free ex tracts of C. thermoacetic1m� have shown incorporation, in the presence of the pyruvate, of the methyl group of N5-methyltetrahydrofolate into the me thyl group of acetate (177,243), and the formation of methyl-cobalamin from reduced B12 (153 ). Experiments on the immediate source of the methyl group and on its transformation to the carboxymethyl group (176) remain to be done.…”

Section: Methyl Corrinomsmentioning

confidence: 99%

Microbial Biosynthesis of B12-Like Compounds

Friedmann¹,

Cagen²

1970

Annu. Rev. Microbiol.

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Section: Methyl Corrinomsmentioning

confidence: 99%

Microbial Biosynthesis of B12-Like Compounds

Friedmann¹,

Cagen²

1970

Annu. Rev. Microbiol.

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“…Raised fasting pyruvate levels were also noted in anaemia of nutritional folate deficiency. It may well be that raised pyruvate levels in these 2 de ficiency states reflect interference with the conversion of pyruvate to ace tate which, in Clostridium thermoaceticum at least requires both vitamin B12 and folate as essential co-factors [14].…”

Section: Discussionmentioning

confidence: 99%

Anaemia and Erythrocyte Transketolase Activity

Wells

1972

Acta Haematol

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Erythrocyte transketolase activity is raised in megaloblastic anaemia due to vitamin B₁₂ deficiency and inversely related to haemoglobin concentration. It si usually normal in cases of megaloblastic anaemia due to folate deficiency though sufficient exceptions occur to invalidate the use of red cell transketolase assay in differentiation of vitamin B₁₂ from folate deficiency.There is no evidence that altered thiamine metabolism is a factor in the disturbance of pyruvate metabolism that occurs in vitamin B₁₂ deficiency, nor that thiamine deficiency is involved in the commonly associated neuropsychiatric disorder.Erythrocyte transketolase activity is normal in untreated iron deficiency anaemia, aplastic anaemia, polycythaemia, chronic myeloid and lymphatic leukaemia, erythroleukaemia and non-anaemic patients with glucose-6-phosphate deficiency. Increased red cell transketolase activity is seen in iron deficiency anaemia responding to treatment, hereditary spherocytosis and occasionally in patients with an autoimmune haemolytic anaemia or acute leukaemia.

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“…The overall mechanism of the total synthesis of acetate from C02 by Clostridium thermoaceticum is gradually being defined (5,7) and may occur as outlined in reactions 1 to 8, in which corrinoid-E is an enzyme-corrinoid complex, THF is tetrahydrofolate, ADP is adenosine diphosphate, Pi is inorganic phosphate, NADP is nicotinamide adenine dinucleotide phosphate, and NADPH is reduced nicotinamide adenine dinucleotide phosphate. 4 Pyruvate + 4 ADP + 4 Pi + 4 NADP 4 acetate + 4 CO2 + 4 ATP + 4 NADPH + 4 H+ (1) CO2 + NADPH + H+ =it HCOOH + NADP+ (2) THF + HCOOH + ATP z formyl-THF + ADP + Pi Formyl-THF + 2 NADPH + 2 H+ ) ) ) CHs-THF + 2 NADP+ CHa-THF + corrinoid-E THF + CH3-corrinoid-E CO2 + CH3-corrinoid-E + ATP -) HOOC-CH2-corrinoid-E + ADP + Pi…”

mentioning

confidence: 99%

“…(8) The most important evidence for this sequence is the following. CO2 is converted to a methyl which is linked to the cobalt of corrinoids (1,4), and this methyl is converted to the methyl of acetate (4, 6) in fermentations of pyruvate by extracts of C. thermoaceticum. Furthermore, '4CH3-THF is converted to the methyl of acetate under similar conditions (5), and, in addition, carboxymethyl-B12 is reduced to acetate (4) (reactions 5 to 7).…”

mentioning

confidence: 99%