B12 vitamins (cobalamins). 1. Vitamins B12<i>c</i> and B12<i>d</i>

Smith, E. Lester; Fantes, K. H.; Ball, S.; Waller, J. G.; Emery, W. B.; Anslow, W. K.; Walker, A. D.

doi:10.1042/bj0520389

Cited by 20 publications

(20 citation statements)

References 17 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…However, the reduced form of aquacobalamin binds NO rapidly and reversibly to form nitroxylcobalamin, CblNO: [7] Nitroxylcobalamin is oxygen sensitive; in the presence of air it rapidly oxidizes to nitrocobalamin CblNO 2 [11]. Nitrocobalamin is one of the naturally occurring forms of (1) Cbl(II) + NO ⇄ Cbl(III)NO − cobalamin and was isolated from biological samples, thus it is stable in biological systems [12,13].…”

Section: Electronic Supplementary Materialsmentioning

confidence: 99%

See 1 more Smart Citation

Mechanistic information on the nitrite-controlled reduction of aquacob(III)alamin by ascorbate at physiological pH

et al. 2015

View full text Add to dashboard Cite

The interaction with nitric oxide (NO) is an important aspect of the biological activity of vitamin B12 (Cbl). Whereas the formation of nitroxylcobalamin (CblNO) via the binding of NO to reduced CblCo(II) has been studied in detail before, the possible intracellular formation of CblNO via reduction of nitrocobalamin (CblNO2) is still questionable. To study this further, spectroscopic and kinetic studies on the reaction of CblNO2 with the intracellular antioxidant ascorbic acid (Asc) were performed in aqueous solution at the physiological pH of 7.2. It was found that the redox pathway of this reaction requires anaerobic conditions as a result of the rapid re-oxidation of reduced CblCo(II). In the studied system, both CblOH2 and CblNO2 are reduced to CblCo(II) by ascorbate at pH 7.2, the CblOH2 complex being two orders of magnitude more reactive than CblNO2. Clear evidence for redox cycling between CblOH2/CblNO2 and CblCo(II) under aerobic conditions was observed as an induction period during which all oxygen was used prior to the formation of CblCo(II) in the presence of an excess of ascorbate. No evidence for the intermediate formation of CblNO or NO radicals during the reduction of CblNO2 could be found. Nitrocob(III)alamin can be reduced by ascorbic acid under physiological conditions. The products of the reaction are cob(II)alamin and nitrite ion. This reaction is ca. 200 times slower than the one involving aquacob(III)alamin.

show abstract

Section: Electronic Supplementary Materialsmentioning

confidence: 99%

“…This suggests that CblNO 2 is reduced to Co(II)Cbl and/or CblNO, but since these species are very oxygen sensitive they are rapidly reoxidized to CblNO 2 . In addition, oxygen can also be consumed by the oxidation of ascorbate to dehydroascorbate (DHA) as indicated in reaction (6) [13].…”

Section: Role Of Oxygenmentioning

confidence: 99%

Mechanistic information on the nitrite-controlled reduction of aquacob(III)alamin by ascorbate at physiological pH

et al. 2015

View full text Add to dashboard Cite

show abstract

“…Nitrocobalamin (NO 2 Cbl) is also a biologically important vitamin B 12 metabolite. 11,20 NO 2 Cbl is the aerobic decomposition product of nitrosylcobalamin, NOCbl, 70,71 and it has been postulated that NOCbl is a naturally occurring B 12 derivative. 11,[94][95][96][97] Evidence suggesting the biological relevance of reactions between nitric oxide and cobalamins include the observation that addition of hydroxycobalamin can diminish the biological effect of NO, 98,99 and the inhibition of vitamin B 12 -dependent methionine synthase and methylmalonylCoA mutase by NO both in vitro and in vivo.…”

Section: Synthesis and Characterization Of Sulfitocobalamin And Nitromentioning

confidence: 99%

“…[7][8][9][10] Sulfitocobalamin (SO 3 Cbl − ) is also isolable from mammalian cells and foods, [9][10][11][12][13][14][15][16][17][18][19] and there are also reports of the isolation of nitrocobalamin (NO 2 Cbl) from biological sources. 11,20 Whether or not cyanocobalamin is truly 'naturally occurring' is controversial; some studies report small amounts of this derivative, especially in smokers. 7,21 Thiol derivatives of B 12 , thiolatocobalamins, were first identified in the 1960s, but have not attracted much attention until recently.…”

Section: Introductionmentioning

confidence: 99%

“…Although both are isolable from biological samples, [11][12][13][14][15][16][17]20 and are well studied and structurally characterized, 23,29,38,43,[59][60][61][62][63][64][65][66][67][68][69] neither are commercially available. NO 2 Cbl is also of interest, since if nitrosylcobalamin (NOCbl) is formed in biological systems to any appreciable extent, NO 2 Cbl rather than NOCbl will be isolated after typical (aerobic) isolation and purification procedures.…”

Section: Introductionmentioning

confidence: 99%

See 1 more Smart Citation

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

et al. 2006

View full text Add to dashboard Cite

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.

show abstract

Recent Advances in Nutrition and Metabolism

Unglaub¹

1954

AMA Arch Intern Med

View full text Add to dashboard Cite

A SMALL monograph entitled "Present Knowledge in Nutrition" has been published recently.1 This should prove a most useful reference ; sections dealing with calories, protein, fat, carbohydrate, minerals, and vitamins are included. VITAMIN A Cama and associates * reported further studies of the characteristics of vitamin A and related compounds. Kaiser and Kagan 6 have described a technique for the determination of vitamin A in feces.Prolonged administration of quinacrine (Atabrine) to rats was found to result in damage to the liver and impairment of the ability of this organ to store vitamin A. Absorption of vitamin A and carotene was depressed by the drug.7The administration of excessive amounts of vitamin A to rats and other animals accelerates the growth and maturation of epiphyseal cartilage cells and the remodeling process which accompanies bone growth. Such effects are suggestive of hormonal action, possibly that of the anterior pituitary. However, studies by Wolbach and Maddock 8 in hypophysectomized rats have shown that these effects occur in the absence of the pituitary and in spite of marked atrophy of the adrenal glands. Similar effects have been observed upon the addition of excessive amounts of vitamin A to the medium containing tissue culture of bone from chick embryos.9 The changes observed in tissue culture are qualitatively similar to those seen in animals made hypervitaminotic by feeding large amounts of vitamin A.f The use of tissue culture techniques appears to offer distinct advantages in the study of the effects of vitamin A upon tissues.14 An unusual case of vitamin A deficiency in a 5 J^-month-old infant was reported by Cornfeld and Cooke.15 Facial palsy and increased intracranial pressure observed in this patient might possibly be attributed to compression of tissues of the growing central nervous system by failure of normal growth of the axial skeleton, which has been observed in various mammalian species and, more recently, in the chicken and duck.| weeks. Definite beneficial effects of this therapy upon localized conjunctival thickening, blepharoconjunctivitis, and "toad skin" were observed. Follicular hyperkeratosis of the forearms persisted in five of eight patients, and improvement in dark adaptation was observed in only 4 of 17 subjects. Kaser and associates 1T reported that patients with a sprue-like syndrome showed no increase in serum vitamin A levels after oral administration of the vitamin given in either the ester or the alcohol form. Patients with chronic pancreatic disease showed no change in serum levels of the vitamin after administration of its ester form, but they were found to have an increase in serum vitamin A after administra¬ tion of the alcohol form.Steigmann and co-workers 18 confirmed the previously reported interference with absorption of vitamin A by mineral oil given close to mealtimes. However, the usual therapeutic dose (30 cc.) of the oil given at bedtime was without effect upon plasma vitamin A levels.Kagan and Kaiser 19 found high concentrations of v...

show abstract

B12 vitamins (cobalamins). 1. Vitamins B12c and B12d

Cited by 20 publications

References 17 publications

Mechanistic information on the nitrite-controlled reduction of aquacob(III)alamin by ascorbate at physiological pH

Mechanistic information on the nitrite-controlled reduction of aquacob(III)alamin by ascorbate at physiological pH

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

Recent Advances in Nutrition and Metabolism

Contact Info

Product

Resources

About