Spinach ferredoxin is a calcium-binding protein

摘要

Spinach-leaf ferredoxin was identified as a calcium-binding protein by45Ca autoradiography on nitrocellulose membranes and with the cationic carbocyanine dye 1-ethyl-2-3-(1-ethylnaphtho1,2-dthiazolin-2-ylidene)-2-methylpropenylnaphtho1,2-dthiazolium bromide (“stains-all”). Binding of45Ca was observed at pH 6.8 and pH 7.8 and in the presence of 5 mM and 20 mM MgCl2. At the higher MgCl2concentration the Ca2+-binding capacity is reduced. Only micromolar concentrations of LaCl3, however, are required to achieve a similar effect. Both the oxidized and reduced forms of ferredoxin bind calc