TABLE 1.
Name, abbreviations, and definitions of compounds relevant to B12 biosynthesis
| Corrinoid | A general term that refers to cyclic tetrapyrroles in which two of the imidazole rings are directly linked together. This structure is known as the corrin ring. In corrinoids, a cobalt ion is held through interactions with each of the pyrrolic nitrogen atoms. |
| Cobamide | A corrinoid with a nucleotide attached to a substituent of the corrin ring. The nucleotide is located on the alpha face [(Co(α)] of the corrin ring, features an alpha N-glycosidic bond and its nucleobase may or may not form a coordination bond with the Co ion of the corrin ring. Cbas are also referred to as complete corrinoids. |
| Incomplete corrinoid | A corrinoid that lacks parts of or the entire α-nucleotide. |
| Cobalamin (Cbl) | Cba whose nucleobase is 5,6-dimethylbenzimidazole. |
| Cyanocobalamin (CNCbl) | Cbl with a cyano group as its upper Co(β) ligand; CNCbl is a synthetic derivative Cbl; cells do not synthesize CNCbl. |
| Vitamin B12 | A synonym of Cbl. |
| Adenosylcobalamin (AdoCbl) | Cbl with a 5-deoxyadenosine (Ado) upper Co(β) ligand. |
| Adenosylcobalamin-5′ phosphate | AdoCbl containing a phosphoryl group on the 5′ carbon of the ribosyl moiety of the nucleotide. |
| Coenzyme B12 | A synonym of AdoCbl. |
| Adenosylcobamide | A Cba with a 5-deoxyadenosine (Ado) upper Co(β) ligand, and any nucleobase other than DMB or adenine. |
| Adenosylpseudocobalamin | A Cba with a 5-deoxyadenosine (Ado) upper Co(β) ligand, and adenine as its nucleobase. |
| Adenosylcobyric acid | An incomplete corrinoid that lacks the entire nucleotide and the 3-aminopropanol moiety to which it is attached to the corrin ring. |
| Adenosylcobinamide (AdoCbi) | An incomplete corrinoid that lacks the nucleotide but retains the 3-aminopropanol moiety that links the ring to the loop. |
| Adenosylcobinamide-phosphate (AdoCbi-P) |
AdoCbi with a phosphoryl group attached to the hydroxyl group of the 3-aminopropanol moiety of the structure. |
| Adenosylcobinamide-GDP (AdoCbi-GDP) |
AdoCbi-P to which a GMP moiety has been attached via a phosphodiester bond. |
| 3-Aminopropanol (AP) | The moiety that tethers the nucleotide to the corrin ring. |
| 3-Aminopropanol-phosphate (AP-P) | The phosphoryl group of AP-P is covalently linked to the 3′ OH group of the ribosyl moiety of the α-nucleotide forming a phosphodiester bond. |
| 5,6-Dimethylbenzimidazole | The nucleobase of cobalamin. |
| α-Ribazole | The α-nucleoside of DMB. |
| α-Ribazole-5′-phosphate | The α-nucleotide of DMB. |