Structure, Constitution and Properties of Vitamin B12

Vitamin B₁₂,the largest molecule with a molecular weight of >1000 g, is a water-soluble vitamin. The chemical structure of vitamin B₁₂ comprises four pyrroles in the centre of a corrin ring and a Co atom binds to (ribose)-5,6-dimethylbenzimidazole. The X-ray crystal diffraction analysis of vitamin B₁₂ offered the first insights into a corrin complex with a biosynthetic and structural relative to natural porphyrins. The main properties of vitamin B₁₂ are as follows: Vitamin B₁₂ is very stable at high temperatures if the pH is between 4.5 and 5.0, whereas the strongly acidic and highly alkaline environment loses its vitamin capacity. It favours proper absorption of calcium. Vitamin B₁₂ is negatively affected by oestrogen, sleeping pills, alcohol, etc. It favours the metabolism of food (fats, carbohydrates and proteins). Vitamin B₁₂ is well soluble in methanol, ethanol and water.