Purification and Biochemical Assay of Synexin and of the Homologous Calcium-Dependent Membrane-Binding Proteins, Endonexin II and Lipocortin I

This chapter describes purification of synexin and methods for analyzing synexin activity. To measure synexin activity, a recording spectrophotometer such as the Gilson 250 can be used, with which four samples can be measured at one time. In addition, a four-cuvet holder is needed, as are the cuvets. The cuvets can either be quartz or acrylic plastic, and of a size suitable for holding 1 ml total volume. The recorder should be set with a full scale of OD 0.2 at 540 nm. The instrument can be temperature statted with a circulating water pump, but routine assays are usually performed at room temperature. The chapter also describes techniques for purifying and assaying endonexin II and lipocortin I.