Phosphagen (guanidino) kinases such as arginine kinase and similar enzymes.
Eukaryotic arginine kinase-like phosphagen (guanidino) kinases are enzymes that transphosphorylate a high energy phosphoguanidino compound, like phosphoarginine in the case of arginine kinase (AK), which is used as an energy-storage and -transport metabolite, to ADP, thereby creating ATP. The substrate binding site is located in the cleft between the N and C-terminal domains, but most of the catalytic residues are found in the larger C-terminal domain. Besides AK, one of the most studied members of this family, this model also represents a phosphagen kinase with different substrate specificity, hypotaurocyamine kinase (HTK).
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