Mutant hemoglobin stability depends upon location and nature of single point mutation

The temperature dependence of the rates of heme release from the β subunits of methemoglobin A and 5 β mutant methemoglobins has been determined. The rates were largest fort wo hemoglobins with mutations distal to heme, previously known to be unstable. The other 3 mutants also released heme faster than A. These hemoglobins, with single point mutations at the α 1β 2 interface, were previously thought to be stable. The low reported yields of the 5 mutant protein covaries with the relative rates of heme release from the met species.