Ligand binding on to maize (Zea mays) malate synthase: a structural study.

A kinetic and ligand binding study on maize (Zea mays) malate synthase is presented. It is concluded from kinetic measurements that the enzyme proceeds through a ternary-complex mechanism. Michaelis constants (Km,glyoxylate and Km,acetyl-CoA) were determined to be 104 microM and 20 microM respectively.

A specific association between the glyoxylic-acid-cycle enzymes isocitrate lyase and malate synthase.

There is accumulating evidence that metabolic pathways are organized in vivo as multienzyme clusters or metabolons. To assess interactions between consecutive enzymes of a pathway in vitro, it is usually essential to modify the physical properties of water around the enzymes, e.g.

Purification of the glyoxylate cycle enzyme malate synthase from maize (Zea mays L.) and characterization of a proteolytic fragment.

A purification scheme is described for the glyoxylate cycle enzyme malate synthase from maize scutella. With our procedure, large amounts of extremely pure enzyme can easily be prepared. Purification involves a heat denaturation step, followed by ammonium sulfate precipitation, and chromatography on DEAE-cellulose and Blue Dextran-Sepharose.

Immobilized enzymes as tools for the demonstration of metabolon formation. A short overview.

In recent years it has become clear that a cell cannot be visualized as a 'bag' filled with enzymes dissolved in bulk water. The aqueous-phase properties in the interior of a cell are, indeed, essentially different from those of an ordinary aqueous solution. Large amounts of water are believed to be organized in layers at the surface of intracellular structural proteins and membranes.

The purification and physicochemical characterization of maize (Zea mays L.) isocitrate lyase.

A purification scheme is described for the glyoxylate cycle enzyme isocitrate lyase from maize scutella. Purification involves an acetone precipitation and a heat denaturation step, followed by ammonium sulfate precipitation and chromatography on DEAE-cellulose and on blue-Sepharose. The latter step results in the removal of the remaining malate dehydrogenase activity, and of a high molecular mass (62 kDa) but inactive degradation product of isocitrate lyase.

Clustering of sequential enzymes in the glycolytic pathway and the citric acid cycle.

In recent years, evidence has been accumulating that metabolic pathways are organized in vivo as multienzyme clusters. Affinity electrophoresis proves to be an attractive in vitro method to further evidence specific associations between purified consecutive enzymes from the glycolytic pathway on the one hand, and from the citric acid cycle on the other hand. Our results support the hypothesis of cluster formation between the glycolytic enzymes aldolase, glyceraldehydephosphate dehydrogenase, and triosephosphate isomerase, and between the cycle enzymes fumarase, malate dehydrogenase, and citrate synthase.

The visualization by affinity electrophoresis of a specific association between the consecutive citric acid cycle enzymes fumarase and malate dehydrogenase.

Evidence is growing that the citric acid cycle, like many other metabolic pathways, might exist in vivo as a more or less tightly organized multi-enzyme cluster. The term 'metabolon' [Robinson, J. B.

Enzyme-enzyme interactions as modulators of the metabolic flux through the citric acid cycle.

A general analysis of the regulation of the citric acid cycle is hampered by the intimate interplay believed to exist between the various surrounding pathways. Two main regulatory mechanisms are thought to determine the flux through the cycle: (1) regulation of individual cycle enzymes, and (2) reversible complex formation between various enzymes of the cycle and related pathways. The latter mechanism allows a cell to maintain a high flux of substrates with a moderate number of intermediates, and offers a means of metabolite channeling.

The immuno-histochemical localization of lectin in pea seeds (Pisum sativum L.).

The lectin from the garden pea (Pisum sativum L.) has been localized at the ultrastructural level by the unlabeled peroxidase-antiperoxidase procedure of L.A.