THE INTERACTION OF METAL-IONS WITH ANNEXIN-V - A CRYSTALLOGRAPHIC STUDY

Three closely related rhombohedral crystal structures of human annexin V have been analysed and compared: a low-calcium, a high-calcium and an ytterbium-soaked crystal. The occupancy of the calcium sites increa ses at higher calcium concentrations, but the calcium is removed rathe r than replaced during soaking in the ytterbium solution. Instead, oth er sites are substituted at high calcium concentrations as well as in the presence of ytterbium. Furthermore, a new site is revealed in the ytterbium-soaked crystal which may give a clue to the mechanism of con formational change that takes place in the third domain of annexin V i n the presence of very high calcium concentrations and of phospholipid s.