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E Latzko

Publications and source records attributed to E Latzko.

8 recordsLinked to original sources
PubMed1978

Purification and properties of spinach leaf cytoplasmic fructose-1,6-bisphosphatase.

Cytoplasmic fructose-1,6-bisphosphatase has been purified from spinach leaves to apparent homogeneity. The enzyme is a tetramer of molecular weight about 130,000. At pH 7.5, the Km for fructose 1.6-bisphosphate was 2.5 micron, and for MgCl2 0.13 mM; the enzyme was specific for fructose 1,6-bisphosphate. Saturation with Mg2+ was achieved with lower concentrations at pH 8 than at pH 7. AMP and high concentrations of fructose 1,6-bisphosphate inhibited enzyme activity. Ammonium sulfate relieved the latter inhibition but was itself inhibitory when substrate concentrations were low. Acetylation studies demonstrated that the AMP regulatory site was distinct from the catalytic site. Cytoplasmic fructose-1,6-bisphosphatase may contribute to the regulation of sucrose biosynthesis in plant leaves.

Cytoplasm↗
PubMed1976

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.

Chloroplasts↗
PubMed1975

Properties and regulation of C-1-fructose-1,6-diphosphatase from spinach chloroplasts.

Chloroplast fructose diphosphatase (EC 3.1.3.11) was purified according to the procedures of Racker and Schroeder [1] and Buchanan et al. [2] and the properties compared. Neither preparation contained fructose diphosphatase from the cytoplasm. The preparations had similar molecular weights, pH optima, affinites for fructose diphosphate and Mg-2+ and were similarly activated by EDTA, dithiothreitol and cystamine. Mg-2+, fructose diphosphate and dithiothreitol all activate chloroplast fructose diphosphatase more so at suboptimal pH values. The combined effects of these substances under estimated physiological conditions in the chloroplast stroma in the light and in darkness were consistent with almost full activity of the enzyme during illumination but no activity in the dark.

Chloroplasts↗