Conformational changes of 4-carboxyglutamic acid-containing protein from bovine bone by binding of alkaline earth...

The effect of magnesium, calcium, and strontium ions on the bovine bone Gla protein were studied by CD spectroscopy, UV difference spectroscopy and the binding of magnesium and calcium ions was studied by equilibrium dialysis. CD measurements indicate an increase of alpha-helix upon addition of alkaline earth ions. UV difference spectra show a change in the environment of a tyrosine residue. Evaluation of the results of all three studies indicate positive cooperativity in binding of calcium and strontium ions and negative or no cooperativity in binding of magnesium ions.