SUMMARY or SPECTROSCOPIC PROPERTIES 229 



(a) Bands of roughly equal strength: HbOo, HbCO, HbNO, denatured 



globin carbon monoxide hemochrome. 



(6) First band stronger; denatured globin hemochrome (other hemo- 



chromes) . 



(c) Second band stronger: denatured globin cyanide ferroporphyrin 



(dicyanide ferroporphyrin) . 



Class II 



2. Ferric compounds with two bands in the green, covalent bonds: hemi- 

 globin hydroxide (essentially), denatured globin hemi'chrome. 



3. Ferric compounds with one band in the green, covalent bonds: hemfglobin 

 cyanide . 



Class III 



Jf.. Ferrous compounds with one band in the green, ionic bonds: hemoglobin 

 (heme). 



Class I 



5. Ferric compounds with a band in the red, ionic bonds: hem/globin and 

 many hemoglobin compounds, acid hematin. 



This classification as well as that of Theorell must be considered a 

 scheme to memorize the main features of the absorption spectra 

 rather than an expression of a natural law, although a deeper connec- 

 tion between absorption spectra and bond types undoubtedly exists. 

 On closer examination, for instance, it becomes likely that the one 

 absorption band in the green part of the spectrum shown by hemo- 

 globin as well as by hemrglobin cyanide consists of two bands com- 

 bined in one. This is indicated in hemoglobin by a slight bulge of 

 the slope of the band toward longer wavelengths, which is more 

 clearly visible in myohemoglobin (Kiese and Kaeske, 1527), and in 

 hemiglobin cyanide only by the less steep fall of the curve from the 

 absorption maximum toward longer wavelengths. 



A more fundamental analysis of the absorption spectra of hemo- 

 globin compounds as being composed of bands belonging to two 

 different series has been attempted by Drabkin (616,618). According 

 to this interpretation the bands in the ultraviolet, the Soret bands, 

 and some bands in the visible are derived from one series, and the 

 typical bands of HbOa, HbCO, HbXO in the visible part of the 

 spectrum from another; the spectra of ferrous compounds have an 

 essentially similar pattern. This analysis still requires confirmation. 



Beer's law is valid for most hemoglobin compounds, except for acid 

 hematin, in a wide range of concentration (Butterfield, Heubner, and 

 Rosenberg; Suhrmann and Kollath; cf. Drabkin, 637). 



