PEPTIDES ARE RESEARCH CHEMICALS, NOT INTENDED FOR HUMAN CONSUMPTION 
Vitamin B12 is a coordination complex of cobalt, which occupies the center of a corrin ligand and is further bound to a benzimidazole ligand and adenosyl group.
Several related species behave similarly to function as vitamins. This collection of compounds is sometimes referred to as "cobalamins". These chemical compounds have a similar molecular structure, each of which shows vitamin activity in a vitamin-deficient biological system. They are referred to as vitamers having vitamin activity as a coenzyme, meaning that its presence is required for some enzyme-catalyzed reactions.