Ferrihaetnoprotein Hydroxides 141 



from one haemoprotein to another as there are for other complexes, e.g. the cyanides 

 and the fluorides. We regard these analyses rather as semiquantitative evidence for 

 the existence of a thermal mixture, in that the calculated band maxima for the two 

 forms occur at appropriate wavelengths with extinction coefficients of the right magni- 

 tude. The spectra of the two forms calculated from the temperature dependence of 

 the spectrum and magnetic susceptibility of a single haemoprotein derivative, e.g. 

 ferrimyoglobin hydroxide in Section V, are however free from this uncertainty. 



Lemberg: Applying similar spectrophotometric methods to those used by George, 

 Beetlestone and Griffith, we find that in contrast to horseradish peroxidase itself, the 

 compound of haematin a with the apoprotein of horseradish peroxidase has the most 

 'high-spin type' of spectrum of the haemoproteins a which we studied. There is thus 

 an interesting difference between two compounds of the same protein with the two 

 diff"erent haematins, haematin a and protohaematin. 



O'Hagan : Preliminary results suggest that aetiohaematin does not attach to apomyoglobin 

 at pH values higher than about pH 8. Holden and Hicks {Aiist. J. exp. Biol. med. Sci. 

 10, 219, 1932) considered alkaline ferrihaemoglobin to be a mixture of a compound 

 in which linkage was not through the iron atom, and globin ferrihaemochrome. My 

 results would appear to confirm this view and would seem to have some bearing on 

 these results of George. 



