Self-organization is a behavior of nonequilibrium systems that is characterized by the development of highly ordered structures from an originally homogeneous state. A necessary prerequisite for this type of pattern formation is the coupling of a feedback regulated reaction with transport processes. Under these circumstances traveling reaction/diffusion waves can develop. The propagation dynamics of such waves display specific features, e.g.: unidirectional propagation due to a refractory zone in the back of the wave, -relation between velocity and curvature of the wave, break-up of circular wave fronts leading to formation of rotating spirals, their trajectory depending on the system's excitability, a decrease in the wave velocity of subsequent following waves with the frequency of wave initiation (dispersion relation). Reaction-diffusion waves may be involved in biological information processing, since they can translate the complexity of metabolic interactions into ordered spatio-temporal structures. We used yeast extract as an experimental system to investigate the mechanisms of biological selforganization. In previous studies we have shown that glycolytic sugar degradation in yeast extracts leads to the spontaneous formation of traveling NADH and proton waves [1, 2]. The state of wave generation is preceded by an induction period lasting about 1 h. This indicates that accumulation of glycolytic intermediates and/or end products is necessary for the transition to excitability. We simulated the accumulation of end products by addition of pyruvate to the yeast extract from the beginning of the experiment. However, this did not lead to remarkable shortening of the induction period with pyruvate additions up to 40 mmol/L. Accumulation of glycolytic intermediates seems to be a more important aspect for the transition of the yeast extract to an excitable state with concomitant wave generation. Another molecular species exhibiting accumulation during glycolytic sugar degradation is protons [3]. Additionally, the key enzyme of oscillatory glycolysis, phosphofructokinase, displays pH-dependent activity having its pH optimum at pH 6.5. We changed the pH of the yeast extract in order to examine whether pH effects are responsible for the emergence of the induction period. Varying the pH between pH 6-7 did not induce strong changes of the induction period. Besides examining the mechanisms that lead to glycolytic excitability, we intend to investigate wave dynamics. We have already shown that the feedback regulated reaction of the phosphofructokinase is crucial for the control of wave initiation and pattern dynamics: controlled wave initiation could be performed by local injection of fructose-2,6-bisphosphate into the yeast extract and the propagation dynamics was markedly changed by AMP addition [2]. Since adenine nucleotides are involved in feedback regulation of phosphofructokinase, we assumed that the energy charge influences wave propagation dynamics. In fact, when changing the energy charge by means of addition of purified plasma membrane ATPase to the yeast extract we could observe the emergence of NADH phase waves (irregular spots of NADH increase). The phase waves developed in front of NADH reaction-diffusion waves and thence they spread over the entire probe, thereby annihilating the reaction-diffusion waves. Obviously, the energy charge changes the dynamics of glycolysis and allows the coexistence of two different states of wave generation (phase waves and reaction-diffusion waves). These findings provide the first indication that the energetic status of the metabolism is reflected in the dynamics ofglycolytic self-organization.