Catalyzes the reversible transfer of the terminal phosphate group between ATP and AMP. Plays an important role in cellular energy homeostasis and in adenine nucleotide metabolism. Has a broad specificity for nucleoside triphosphates, being highly active with ATP or dATP as phosphate donors, and less active with GTP or UTP. AMP + ATP = 2 ADP Competitively inhibited by the bisubstrate analog Ap5A, by 7-deazaadenosine 5'-monophosphate (TuMP) and 8-bromo-AMP. Optimum temperature is 50-55 degrees Celsius. Highly thermostable. Is half-inactivated at about 67 degrees Celsius. Purine metabolism; AMP biosynthesis via salvage pathway; AMP from ADP: step 1/1. Monomer. Consists of three domains, a large central CORE domain and two small peripheral domains, NMPbind and LID, which undergo movements during catalysis. The LID domain closes over the site of phosphoryl transfer upon ATP binding. Assembling and dissambling the active center during each catalytic cycle provides an effective means to prevent ATP hydrolysis. The LID domain is a solvent-exposed domain that is much shorter in Mycobacterium than in many other bacteria like E.coli. Belongs to the adenylate kinase family.