Analysis and Interpretation of Absorption Spectra of Haemin Chromoproteins 163 



carbonyl derivatives), indicating tliat the CoHg and CH3CH2COOH side 

 chains had individually no distinguishable spectroscopic affects, but the 

 maxima in the spectra of all protohaemin complexes were shifted some 10 m^« 

 toward the longer wavelengths. Three distinctive spectroscopic patterns were 

 found for all the ferrohaems, characteristic for the combination with 



620 580 540 500 



A, m/^ 



Fig. 15. The three distinctive spectral patterns exhibited by ferrohaems co- 

 ordinated with three types of ligands, exemplified by derivatives of ferromeso- 

 porphyrin. Curve 1, cyanide ferromesoporphyrin, representative of Pattern Type 

 1. Curve 2, pyridine ferromesoporphyrin, representative of Pattern Type 2. 

 Curve 3, carbonyl ferromesoporphyrin, representative of Pattern Type 3. In all 

 cases the NaOH concentration was 0-2 m/1. and the NagSjOi concentration 5 mM/1. 

 The pyridine concentration was 6-19 m/1. and that of cyanide 400 mM/1. The 

 horizontal arrows and appended numbers represent the magnitude in m/i of the 

 shift of maxima towards longer wavelengths in corresponding derivatives of 

 ferroprotoporphyrin (Drabkin, 1942b). 



cyanide, pyridine and carbon monoxide (Fig. 15). These conclusions were 

 reached: (1) The shape and intensity of absorption in the visible region was a 

 function of the nature of the co-ordinating ligand. (2) The wavelength 

 location of the maxima (of the a and /5 bands) was a function of the haemins 

 (or porphyrins) themselves, and most probably of the groups substituted in 

 positions 2 and 4. The maxima in the spectra of haemoglobin derivatives were 

 in the locations expected for protohaemin derivatives. On the other hand, the 



