Activity and NMR structure of synthetic peptides of the bovine ATPase inhibitor protein, IF1

The protein IF1 is a natural inhibitor of the mitochondrial FoF1-ATPase. Many investigators have been propted to identify the shortest segment of IF1, retaining its native activity, for use in biomedical applications. Here, the activity of the synthetic peptides IF1-(42-58) and IF1-(22-46) is correlated to their structure and conformational plasticity determined by CD and (1H)-NMR spectroscopy. Among all the IF1 segment tested, IF1-(42- 58) exerts the most potent, pH and temperature dependent activity on the FoF1 complex. The results suggest that, due to its flexible structure, it can fold in helical and/or b-spiral arrangements tha fovor the binding to the FoF1 complex, where tha native IF1 binds. IF1-(22-46), instead, as it adopts a rigid a-elical conformation, it inhibits ATP hydrolysis only in the soluble F1 mojety.