AMP, adenosine monophosphate, contains adenine, a ribose sugar and one phosphate group. It is formed from the hydrolysis of ATP: ATP + H20 ↔ AMP + PPi, using the enzyme adenylate kinase in a reversible reaction: 2ADP ↔ ATP + AMP, and by the hydrolysis of ADP:
ADP + H20 ↔ AMP + Pi 
AMP is used in regulating the activity of the glutamine synthease enzyme. The addition of AMP to a certain Tyrosine residue via a phosphodiester bond makes the enzyme less active. 
When catabolism of AMP molecules occur, it degrades first to Xanthine then Urate for excretion, utilising many different enzymes in a complicated process.
The enzyme adenylate cyclase can convert ATP into cAMP, regulated by the hormones adrenaline or glucagon, in certain cells.