Kinetic and physico-chemical analysis of enzyme complexes and their possible role in the control of metabolism

Enzyme‐enzyme interactions and their metabolic role

“…A comprehensive review of this area appeared in 1987 [5] and another in 1989 [6]. In this short review we shall limit ourselves to the following areas: (i) new techniques for demonstrating protein-protein interactions;…”

Concentrations of Glycolytic Enzymes and Other Cytosolic Proteins in the Diffusible Fraction of a Vertebrate Muscle Proteome

“…This information could help settle some controversial points debated over the past 50 years, such as whether large supramolecular complexes exist for glycolytic enzymes in the native cytosol (for a summary, see Ref. 5). …”

“…Not only are proteins in dilute slurries isolated under conditions far different from those in intact cells, additional information about their interactions may be lost using conventional methods of fractionation. Enzyme-enzyme interactions constitute an area of intense interest in structural genomics and enzymology (5,6). Clearly studies in these areas would benefit from new approaches for isolation of proteins and determining their concentrations and stoichiometric relationships under conditions more closely approximating their native state.…”

A Specific Association Between the Glyoxylic‐Acid‐Cycle Enzymes Isocitrate Lyase and Malate Synthase

“…In recent years it was realized that the aqueous-phase properties in the interior of a cell seem to be essentially different from those of an ordinary aqueous solution Clegg, 1984;Friedrich, 1986;Keleti et al, 1989;Srere, 1987;Bernhard, 1986, 1987;Wombacher, 1983). It was calculated that protein concentrations in various subcellular compartments may be as high as 0.5 g/ml, which is comparable to the protein concentration in enzyme crystals (Fulton, 1982 ;Hackenbrock, 1968 ;Srere, 1980).…”

“…However, specific associations between enzymes of other metabolic pathways have been amply demonstrated and discussed in the past (see, Beeckmans et al, 1993;Clegg, 1984;Friedrich, 1986;Fulton, 1982;Keleti et al, 1989;Srere, 1987;Bernhard, 1986, 1987;Wombacher, 1983; for reviews on this topic). Such associations between consecutive enzymes of a pathway offer many advantages for the organism, such as: the possibility of passing around intermediates of the pathway without delivering them first to the bulk phase, thereby circumventing diffusion problems ; the possibility of channeling of intermediates within a path- way or towards different metabolic pathways, thereby allowing an immediate and flexible adaptation to the continuously changing needs of the organism; the creation of a special environment around the pathway, so that a high flux can be maintained with a moderate number of intermediate molecules ; protection of labile intermediates by reducing their life-times; extensively speeding up a number of processes by reducing the transient time (i.e.…”