Electrostatic channeling of oxaloacetate in a fusion protein of porcine citrate synthase and porcine mitochondrial malate dehydrogenase.

Mitochondrial malate dehydrogenase and citrate synthase are sequential enzymes in the Krebs tricarboxylic acid cycle. We have shown [Lindbladh, C., Rault, M.

Enzymatic and fluorescence studies of four single-tryptophan mutants of rat testis fructose 6-phosphate,2-kinase:fructose 2,6-bisphosphatase.

In order to determine environments around four tryptophan residues, located in the N-terminus, in the kinase and in the phosphatase domains of rat testis Fru 6-P,2-kinase:Fru 2,6-bisphosphatase, mutant enzymes containing a single tryptophan were constructed by site-directed mutagenesis. The kinetic constants of these mutant enzymes were similar to those of the wild-type enzyme. The sum of the fluorescence intensities of the enzymes was 1.