FELIX HAUROWITZ 



haemoglobin, upon drying in vacuo, undergoes a marked alteration 

 of its absorption spectrum. The broad absorption band of haemoglobin 

 is replaced by two narrow bands of a typical haemochromogen spec- 

 trum. The reaction is completely reversible when water is added and 

 it can be repeated several times without any apparent denaturation of 

 the haemoglobin. 



Globin-W-O z Globin-Ft-H t O Globin-Fe-n \-Globin-Jt- 



n4 n/i ! ^_| ^ n/i 



/ //. m. iv. 



Oxyhemoglobin Haemoglobin Dry Haemoglobin 



(Aquo-Hb) (Anhydro-Hb) 



We have attempted to record the spectral alterations by a quantitative 

 method. The usual spectrophotometry method could not be applied, 

 because dry layers of haemoglobin had to be measured. The height of 

 these layers is not quite uniform. Good results were obtained, however, 

 by making use of spectrography. Figure 1 shows the visible absorption 

 spectra of beef oxyhaemoglobin (a), haemoglobin (b), dry haemo- 

 globin (c), globin-haemochromogen (d) and oxyhaemoglobin obtained 

 by dissolving the dry haemoglobin in water (e). 



It is evident from Figure 1 that the absorption spectrum of dry 

 haemoglobin (c) is very similar to the true haemochromogen spectrum 

 (d) But, on dissolving dry haemoglobin in water and saturating with 

 air a typical oxyhaemoglobin spectrum (e) is obtained. There is no 

 doubt, therefore, that the reaction is completely reversible. 



Similar results were obtained with myoglobin from beef heart and 

 with synthetic haemoglobins. The latter were prepared by coupling 

 native beef globin with protohaemin, mesohaemm or the dimethyl 

 ester of mesohaemin. All of these preparations gave typical haemo- 

 globin spectra, when reduced by small amounts of dithionite^Na^O^ 

 and haemochromogen spectra upon drying in vacuo at 40°C. Dis- 

 solving of the dry haemoglobins in water and saturation with air 

 furnished in all cases typical oxyhaemoglobin spectra. It is evident 

 from these experiments that the observed alteration of the haemoglobin 

 spectrum upon drying is independent of the molecular weight of the 

 globin component (which is lower in myoglobin than m haemoglobin) 

 and that the side chains of the haem component are not involved in 

 this alteration. , 



Since all known haemochromogens contain two substituents linked 

 coordinatively to the iron atom, the same may be assumed for the 

 haemochromogen-like substance formed from haemoglobin on drying. 



54 



