114 



P. George, J. Beetlestone and J. S. Griffith 



band at about 500 m.ii ; and all the low-spin ferric complexes have spectra 

 like the cyanide derivatives, with a very pronounced absorption band at 

 about 540 m/j, and a shoulder, or second band, at about 580 m/« (Theorell, 

 1942). The high-spin complexes have additional minor bands of lower 

 intensity, at about 580 and 540 m/<, but for the present it is the positions of 



1.2 



1.0 



'mM 

 0.8 



0.6 



0.4 



0.2 







+ + + 



■ ^^f 



+ + + 



Mb 



/ \ 



/ N 



/ 



\ 



900 





800 

 ;\(m;j) 



700 



Fig. 7. Near infra-red spectra of ferrimyoglobin fluoride, hydroxide and 

 cyanide, and ferrihaemoglobin hydroxide (Hanania, 1953). 



the major bands which differentiate the two types of complex that are 

 important. 



Similar contrasting features appear in other regions of the absorption 

 spectrum. In the near infra-red the fluoride complex has a v/ell-defined 

 absorption band at about 850 m/( with a shoulder at about 750 m//, whereas 

 the cyanide complex has remarkably low absorption throughout the whole 

 range 700 to 950 m// as shown in Fig. 7 (George and Hanania, 1955). In the 

 ultra-violet, from 280 to 450 m/<, there are three regions to consider. The 

 very intense Soret band lies between 405 and 410 m/t for the acidic ferri- 

 haemoproteins and the fluoride complexes, the latter having lower absorption 

 in the case of myoglobin and haemoglobin but higher in the case of peroxidase. 

 On the other hand, the low-spin derivatives have the band shifted towards 

 the red in the neighbourhood of 418 to 425 m^a (see Fig. 8). Minor bands 

 occur at about 350 m/u. These are unresolved in the case of the acidic ferri- 

 haemoproteins and the fluoride complexes, but two distinct bands at about 



