adenosine diphosphate (ADP) a nucleotide, adenosine 5′-pyrophosphate, produced by the hydrolysis of adenosine triphosphate (ATP). It is then converted back to ATP by the metabolic processes oxidative phosphorylation, glycolysis, and the tricarboxylic acid cycle.adenosine monophosphate (AMP) a nucleotide, adenosine 5′-phosphate, involved in energy metabolism and nucleotide synthesis.t is then converted back to ATP by the metabolic processes oxidative phosphorylation, glycolysis, and the tricarboxylic acid cycle. adenosine monophosphate (AMP) a nucleotide, adenosine 5′-phosphate, involved in energy metabolism and nucleotide synthesis.