Hemoglobin and Cyanide

[Bob Hoesch]

If one is using hemoglobin as a marker for analyzing population   
genetics, a standard procedure is to treat the blood sample with low 
concentrations of cyanide prior to IEF (isoelectric focusing).  This 
results in the elimination of "spurious" bands, and apparently makes    
the resulting banding patterns amenable to genetic analysis. I've heard    
this procedure described as "reduction of methemoglobin" (reduction of     
the oxidized iron back to the reduced state), but this doesn't make sense 
to me in terms of the chemistry. Can someone explain what is happening in 
this cyanide-induced reduction in the number of hemoglobin bands?  How could 
cyanide reduce Fe3+ to Fe2+?