Expression of mutant genes for horse cytochrome c in Escherichia coli

Here we describe genetically engineered constructs for the expression in Es cherichia coli of genes for horse cytochrome c mutants. These constructs al low the expression of the cytochrome c genes together with heme-ligase, an enzyme which covalently links heme to cytochrome. Careful selection of prod ucer strains and the adjustment of the conditions of expression provided fo r expression levels of 10-15 mg of protein per liter of culture. This is by an order of magnitude gl eater than the expression previously achieved in yeast. A series of horse cytochrome c mutants were obtained in this way.