Glutathionylcobalamin as an intermediate in the formation of cobalamin coenzymes

Pezacka, E.; Green, Ralph; Jacobsen, Donald W.

doi:10.1016/0006-291x(90)90351-m

Cited by 89 publications

(88 citation statements)

References 18 publications

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“…7,21 Thiol derivatives of B 12 , thiolatocobalamins, were first identified in the 1960s, but have not attracted much attention until recently. 18,19, Glutathionylcobalamin (GSCbl) is an important cobalamin metabolite in mammals, [31][32][33] and is more active than other cobalamins in promoting methionine synthase activity in rabbit spleen extracts. We proposed that GSCbl (or a closely related thiolatocobalamin adduct) is a precursor of the two coenzyme forms of vitamin B 12 , AdoCbl and MeCbl.…”

Section: Introductionmentioning

confidence: 99%

“…We proposed that GSCbl (or a closely related thiolatocobalamin adduct) is a precursor of the two coenzyme forms of vitamin B 12 , AdoCbl and MeCbl. 41 Formation of GSCbl from H 2 OCbl + and glutathione is irreversible (K obs ~ 3 × 10 8 M −1 at pH 7.4, 25 °C) and rapid (t 1/2 ~ 3 s for [GSH] = 5 mM, pH 7.4, 37 °C). 45 An alternative role for GSCbl was also recently proposed, in which the formation of GSCbl prevents B 12 from being scavenged by xenobiotics.…”

Section: Introductionmentioning

confidence: 99%

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A simple, convenient method to synthesize cobalamins: synthesis of homocysteinylcobalamin, N-acetylcysteinylcobalamin, 2-N-acetylamino-2-carbomethoxyethanethiolatocobalamin, sulfitocobalamin and nitrocobalamin

et al. 2006

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Glutathionylcobalamin, nitrocobalamin and sulfitocobalamin are important cobalamin metabolites isolable from human tissues. Herein we demonstrate that a procedure used to synthesize and isolate γ-glutamylcysteinylcobalamin and glutathionylcobalamin in aqueous solution in high yield and purity can be used to synthesize other novel, biologically relevant thiolatocobalamins, including D,Lhomocysteinylcobalamin, N-acetyl-L-cysteinylcobalamin (Na + salt) and 2-N-acetylamino-2-carbomethoxy-L-ethanethiolatocobalamin, as well as other non-alkylcobalamins, such as sulfitocobalamin (Na + salt) and nitrocobalamin. This uncomplicated, general procedure will assist researchers in identifying unknown cobalamin metabolites isolated from biological samples, and researchers interested in studying the uptake and intracellular cobalamin processing mechanisms utilizing non-alkylcobalamin derivatives that are not yet commercially available. The X-ray structure and XAS spectrum of N-acetyl-L-cysteinylcobalamin are also presented.

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Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

A simple, convenient method to synthesize cobalamins: synthesis of homocysteinylcobalamin, N-acetylcysteinylcobalamin, 2-N-acetylamino-2-carbomethoxyethanethiolatocobalamin, sulfitocobalamin and nitrocobalamin

et al. 2006

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“…The pathway by which X-B12s are converted to Ado-B12 has been studied in several organisms and is thought to be similar in both prokaryotes and eukaryotes (Fig. 1); X-B12 is converted to glutathionyl-B12 (GS-B12), reduced to cob-(II)alamin, further reduced to cob(I)alamin, and finally adenosylated to Ado-B12 (11)(12)(13)(14)(15). In humans, four complementation groups (cblABCD), associated with methylmalonyl aciduria, are thought to correspond to genes involved in the conversion of X-B12s to Ado-B12.…”

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confidence: 99%

Identification of the Human and Bovine ATP:Cob(I)alamin Adenosyltransferase cDNAs Based on Complementation of a Bacterial Mutant

Leal

Park

Kima

et al. 2003

Journal of Biological Chemistry

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In humans, deficiencies in coenzyme B12-dependent methylmalonyl-CoA mutase (MCM) lead to methylmalonyl aciduria, a rare disease that is often fatal in newborns. Such deficiencies can result from inborn errors in the MCM structural gene or from mutations that impair the assimilation of dietary cobalamins into coenzyme B12 (Ado-B12), the required cofactor for MCM. ATP:cob(I)alamin adenosyltransferase (ATR) catalyzes the terminal step in the conversion of cobalamins into Ado-B12. Substantial evidence indicates that inherited defects in this enzyme lead to methylmalonyl aciduria, but the corresponding ATR gene has not been identified. Here we report the identification of the bovine and human ATR cDNAs as well as the corresponding human gene. A bovine liver cDNA expression library was screened for clones that complemented an ATR-deficient bacterial strain for color formation on aldehyde indicator medium, and four positive clones were isolated. The DNA sequences of two clones were determined and found to be identical. Sequence similarity searching was then used to identify a homologous human cDNA (89% identity) and its corresponding gene that is located on chromosome XII. The bovine and human cDNAs were independently cloned and expressed in Escherichia coli. Enzyme assays showed that expression strains produced 87 and 98 nmol/min/mg ATR activity, respectively. These specific activities are in line with values reported previously for bacterial ATR enzymes. Subsequent studies showed that the human cDNA clone complemented an ATR-deficient bacterial mutant for Ado-B12-dependent growth on 1,2-propanediol. This demonstrated that the human ATR is active under physiological conditions albeit in a heterologous host. In addition, Western blots were used to show that ATR expression is altered in cell lines derived from cblB methylmalonyl aciduria patients compared with cell lines from normal individuals. We propose that inborn errors in the human ATR gene identified here result in methylmalonyl aciduria. The identification of genes involved in this disorder will allow improvements in the diagnosis and treatment of this serious disease.

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“…The optimum temperature of the enzyme was determined by incubating at temperatures (10,15,20 Protein assay. Protein was assayed using a Bio-Rad protein assay kit, with ovalbumin as standard according to the manufacturer's instructions.…”

Section: Methodsmentioning

confidence: 99%

Occurrence of 5'-Deoxyadenosylcobalamin and Its Physiological Function as the Coenzyme of Methylmalonyl-CoA Mutase in a Marine Eukaryotic Microorganism, Schizochytrium limacinum SR21

Miyamoto

Tanioka

Yukino

et al. 2007

J Nutr Sci Vitaminol

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Summary A marine eukaryotic microorganism, Schizochytrium limacinum SR21, had the ability to absorb and accumulate exogenous cobalamin, which was converted to the cobalamin coenzymes 5 ¢ -deoxyadenosylcobalamin (20.1%) and methylcobalamin (29.6%). A considerably high activity (about 38 mU/mg protein) of 5 ¢ -deoxyadenosylcobalamin-dependent methylmalonyl-CoA mutase (EC 5.4.99.2) involved in amino acid and odd-chain fatty acid metabolism was found in the cell homogenate of S. limacinum SR21. The enzyme was purified to homogeneity and characterized.

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Glutathionylcobalamin as an intermediate in the formation of cobalamin coenzymes

Cited by 89 publications

References 18 publications

A simple, convenient method to synthesize cobalamins: synthesis of homocysteinylcobalamin, N-acetylcysteinylcobalamin, 2-N-acetylamino-2-carbomethoxyethanethiolatocobalamin, sulfitocobalamin and nitrocobalamin

A simple, convenient method to synthesize cobalamins: synthesis of homocysteinylcobalamin, N-acetylcysteinylcobalamin, 2-N-acetylamino-2-carbomethoxyethanethiolatocobalamin, sulfitocobalamin and nitrocobalamin

Identification of the Human and Bovine ATP:Cob(I)alamin Adenosyltransferase cDNAs Based on Complementation of a Bacterial Mutant

Occurrence of 5'-Deoxyadenosylcobalamin and Its Physiological Function as the Coenzyme of Methylmalonyl-CoA Mutase in a Marine Eukaryotic Microorganism, Schizochytrium limacinum SR21

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