Gabriel G. Bonassi

Introduction Phosphagen kinases play an integral role in the bioenergetics of skeletal and cardiac muscle where they catalyse the conversion of phosphagens to ATP and vice versa (Wallimann et al., 1992). Phosphagen systems maintain deep reservoirs of phosphagens, such as phosphoarginine in fruit flies and phosphocreatine in mammals. These reservoirs make ATP available at times of intense metabolic load acting as ‘temporal’ buffers between energy supply and demand (Newsholme et al., 1978).