Alcoholism cobalamins

Beck and Brink [28] have described a sensitive method for the routine assay of cobalamins in activated sewage sludge. The method involves extraction with benzyl alcohol, removal of interfering substances using a combination of gel filtration and chromatography on alumina, concentration of the extract by lyophilization, and direct determination of total cobalamin by high-speed liquid chromatography, in comparison with cobalamin standards. 

The catalytic isomerization of meso-epoxides to allylic alcohols has been achieved with chiral cobalt complexes, in particular with cobalamin (vitamin B12) [47, 48]. 

Ethanolamine ammonia lyase. EAL converts ethanol-amine to acetaldehyde, with loss of ammonia. EAL depends upon adenosylcobamides, such as coenzyme B12 (3), but a range of other adenosylcobamides are also accepted as cofactors, while cobalamins with /3-ligands other than the 5 -deoxy-5 -adenosyl group (of AdoCbl) are inhibitors. Active EAL is multimeric and has an apparent molecular mass of about 560 600kDa. Similar to the mechanism of DD, a radical mechanism is proposed for the isomerization of the vicinal amino-alcohol substrates (ethanolamine, (/f)- and (5)-aminopropanol) by EAL, starting with the abstraction of an H atom from the C-1 position of the substrates. 

B. Megaloblastic anemia is caused by a decrease in the synthesis of deoxythymidylate and the purine bases usually caused by a deficiency in either THF or cobalamin or both. This results in decreased DNA synthesis, which results in abnormally large hematopoietic cells created by perturbed cell division and DNA replication and repair. This patient exhibits signs of chronic alcoholism, which often leads to a folate deficiency. This can occur due to poor dietary intake, decreased absorption of folate due to damage of the intestinal brush border cells and resulting conjugase deficiency, and poor renal resorption of folate. 

In spite of Jean Ann Tonich s relatively malnourished state because of chronic alcoholism, her serum cobalamin level was still within the low-to-normal range. If her undernourished state had continued, a cobalamin deficiency would eventually have developed. 

Jean Ann Tonich developed a folate deficiency and is on the verge of devel-j oping a cobalamin (vitamin B12) deficiency as a consequence of prolonged moderately severe malnutrition related to chronic alcoholism. Before folate therapy is started, the physician must ascertain that the megaloblastic anemia is not caused by a pure B12 deficiency or a combined deficiency of folate and B12. 

The reaction of cobaloximes and cobalamines with vinyl ethers in the presence of alcohols to give acetals via intermediate cobalt(ni)-alkene complexes (Scheme 7),... 

In many studies on plasma cobalamin forms, the method initially described by Lindstrand and Stahlberg in 1963 (10) is still being used. One volume of plasma is poured into four volumes of absolute alcohol and heated for 20 min at 80 C. After removal of precipitate by filtration the alcohol in the filtrate is evaporated under vacuum at 30°C. The residual water phase is extracted three to six times with ether to remove lipid material. In the next step cobalamins are extracted from the water phase into phenol by shaking in four volumes of phenol with 15% water. The phenol phase is shaken with one part of acetone, three parts of ether, and a small amount of water. Phenol in the resulting water phase is further removed with ether. The water phase containing the cobalamin is evaporated to remove residual ether. Linnell et al. (65,66) used essentially the same procedure with smaller volumes of blood plasma. 

Photolysis of [Co(CH2R)(L)(Hdmg)2] under oxygen proceeds by insertion of dioxygen into the cobalt carbon bond to provide a solution species for which nmr spectroscopic data is rq)orted. Reduction of this intermediate produces primary alcohols whereas thermolysis produces aldehydes and alcohols. Treatment of [Co oep)] with simple aldehydes and rm-butylhydroperoxide in the presence of sodium borohydride produces cobalt(III) acyls in 65-98% yields. In the absence of the borohydride the yield is reduced. The reaction is proposed to proceed by acyl radical trapping by the Co(n) centre. Methyl transfer in a protein free model of vitamin B12 dependent methyl transf enzymes has been studied. These systems convert homocysteine to methionine in nature. Trimethyl-phenylammonium icm reacts with the CoG) centre in cobalamin producing methylcobalamin. ... 

Cobalamin — — Benzyl alcohol extract of water — IpgL [146]... 

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