Calorimetric characterization of the stable complex of myosin subfragment 1 with ADP and beryllium fluoride

Abstract

The thermal unfolding of the myosin subfragment 1 (S1) in its stable complex with ADP and beryllium fluoride (S1.ADP.BeF3-) was studied by differential scanning calorimetry. It has been shown that the structure of the S1 molecule in the S1.ADP.BeF3- complex is similar to that of S1 in its complex with ADP and orthovanadate (S1.ADP.Vi) but differs radically from that of nucleotide-free S1 and S1 in the S1.ADP complex. It is concluded that the S1.ADP.BeF3- complex can be considered, like the S1.ADP.Vi complex, a stable structural analogue of the myosin head.ADP.Pi transition state of the myosin-catalyzed ATP hydrolysis.