STIMULATION OF SPINACH (SPINACIA-OLERACEA) CHLOROPLAST FRUCTOSE-1,6-BISPHOSPHATASE BY MERCURIC IONS

Chloroplast fructose-1,6-bisphosphatase can exist in an active reduced form or a less active oxidised form. Oxidised fructose bisphosphatase from spinach (Spinacia oleracea) could be stimulated up to many hundr ed-fold by 0.1 mM HgCl2 whereas fructose bisphosphatases from rabbit, yeast, a non-chloroplast enzyme from spinach and the reduced chloropla st enzyme were only inhibited by HgCl2. Stimulation of the enzyme was maximal at pH 8.0 and low magnesium concentrations where the oxidised enzyme normally has little activity. (C) 1997 Federation of European B iochemical Societies.