Final answer:
The structure of vitamin B12 can indeed have an adenosyl group in the form of adenosylcobalamin, which is one of its active forms in the body.
Step-by-step explanation:
Yes, the structure of vitamin B12 can have an adenosyl group. In the body, vitamin B12 exists in several forms, and one of these forms is adenosylcobalamin, which indeed contains an adenosyl group attached to the cobalt ion in the center of the corrin ring system. When vitamin B12 is ingested, it has a cyanide ligand, but this is replaced in the body by different organic groups, including the adenosyl group, to form adenosylcobalamin.
Vitamin B12 is a complex molecule and is regarded as the most complex nonpolymeric biological molecule known. Its core features a tetrapyrrole ring structure known as the 'corrin' ring system, with a cobalt atom at the center linked to the nitrogens of the pyrrole rings (corrin ring system, cobalt atom).