FDPases of the castor bean endosperm and leaf: properties and partial purification

Plant fructose-1,6-bisphosphatases: characteristics and properties

In this minireview the properties and characteristics of plant fructose-1,6-bisphosphatases (D-fructose-1,6-bisphosphatase 1-phosphohydrolase, EC 3.1.3.11) are discussed. The properties and characteristics of the chloroplastic and cytoplasmic forms of the enzyme are reviewed. For purposes of comparison some reference is made to fructose-1,6-bisphosphatases from other species.

A new procedure for the purification of spinach leaf photosynthetic fructose-1,6-bisphosphatase by affinity chromatography on mercaptoethylamine-Sepharose

A new purification procedure for spinach leaf fructose-1,6-bisphosphatase is proposed, which includes the use of affinity chromatography on mercaptoethylamine-Sepharose. A homogeneous preparation of the enzyme can be obtained in 48 hr, with a specific activity of 67 U/mg and a yield of 23%. The method may also be useful for the purification of other thioredoxin-activated chloroplast enzymes.

Efficient purification and molecular properties of spinach chloroplast fructose 1,6-bisphosphatase

A relatively straightforward procedure has been developed for the purification of chloroplast fructose bisphosphatase from spinach leaves to apparent homogeneity and with 80% yield. The molecular weight of the enzyme was about 160 000. Chloroplast fructosebisphosphatase consists of four possibly identical subunits and, at pH 8.8, EASILY DISSOCIATES INTO EQUAL HALVES WITH LOWered activity. Sigmoid saturation curves with Hill coefficients between 3.0 and 3.7 were obtained for fructose 1,6-bisphosphate and Mg2+. Incubation of the enzyme with 20 mM dithiothreitol slowly altered the response to pH from no activity measured at pH 7.5 and full activity at pH 8.8 to equal activity at each of these pH values; at the same time the number of freely available sulphydryl groups increased from four to twelve per molecule. These properties are considered in the context of the observed activation of this enzyme following illumination of chloroplasts.