Cobamide coenzyme

NAD and NADP and FMN and FAD, respectively. Pantothenic acid is a component of the acyl group carrier coenzyme A. As its pyrophosphate, thiamin participates in decarboxylation of a-keto acids and folic acid and cobamide coenzymes function in one-carbon metabolism. 

B23. Barker, H., Structure and function of cobamide coenzymes. Federation Proc. 20, 956-961 (1961). 

Barker, H. A., Smyth, R. D., Weissbach, H., Toohey, J. I., Ladd, J. N. and Volcani, B. E. 1960B. Isolation and properties of crystalline cobamide coenzymes containing benzimidazole or 5,6-dimethylbenzimidazole. J. Biol. Chem. 235, 480-488. 

Incorporation of solvent hydrogen into the substrate does not rule out its transfer as hydride if the source of hydride is dithiol, as in the ribonucleotide reductases. In the most understood enzyme of this type, from Lactobacillus leichmannii, the function of the dithiol (45) is to reduce the cobamide coenzyme (46) and provide a source... 

Frey, P. A., Essenberg, M. K., and Abeles, R. H., 1967, Studies on the mechanism of hydrogen transfer in the cobamide coenzyme-dependent dioldehydrase reaction. J. Biol. Chem. 242 5369n5377. 

Cobamide coenzymes are also involved in the degradation of L-lysine to fatty adds and ammonia in Clostridium and the conversion of 1,2-diols to aldehydes in various microorganisms (Fig. 2). 

Cell fractionation studies of homogenates of the gastric mucosa have demonstrated that the intrinsic factor is found both in mitochondria and the supernatant fluid. The factor remains difficult to assay a variety of methods have been used, but none is entirely satisfactory. These methods include (1) administration of intrinsic factor preparation to gastrectomized animals (rats or hogs) (2) measurement of vitamin 6 2 binding capacity of the preparation (3) measurement of vitamin Bi2 uptake in tissue and (4) evaluation of the inhibition of cobamide coenzyme activity in the glutamate isomerase reaction. 

Barker discovered the need for cobamide coenzymes during his studies on the conversion of glutamate to... 

Proc 12th Int Dairy Congr, v 2, pp 619-622 Toohey JI, Perlman D and Barker HA (1961) Purification and properties of cobamide coenzymes obtained from Propionibacterium arabinosum. J Biol Chem 236 2119-2127 Torray JC (1916) Bacteria associated with certain types of abnormal lymph glands. J Med Res 34 65-80... 

Vorobjeva LI and Iordan EP (1976) Functions of cobamide coenzymes in metabolism of propionic acid bacteria. In Chagovets RV (ed) Vitaminy, pp 16-20. Naukova Dumka,... 

RO Brady, EG Castanera, HA Barker. The enzymatic synthesis of cobamide coenzymes. J Biol Chem 237 2325-2332, 1962. 

Vitamin B12 chemistry. The structure of the 5,6-dimethylbenzimidazole-cobamide-coenzyme, as found in the wet crystals, has been determined by X-ray and neutron diffraction (see Figure 59) [123, 124]. A schematic... 

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