adenylate kinase

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An enzyme which catalyses the interconversion of ATP, ADP, and AMP. It forms an enzyme system (the adenylate kinase system ) that is able to provide ATP rapidly during intense activity. In the presence of adenylate kinase, 2 molecules of ADP are converted to 1 molecule of ATP and 1 molecule of AMP. The reaction can take place in both directions, but formation of ATP is favoured if there is an excess of free ADP and the AMP is removed, a situation that occurs during intense activity. The amount of free ADP in muscles is limited and is quickly consumed when the adenylate kinase system is functioning. This system, therefore, is regarded as a reserve energy system used during very intense exercise or when muscle glycogen is depleted.

An enzyme that catalyzes the phosphorylation of one molecule of ADP by another, yielding ATP and AMP.

2 ADP ⇔ ATP + AMP

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