The Ultraviolet Spectral Absorption of 

 Haemoglobins Inside and Outside the Red 



Blood Cell 



E. M. JOPE 



The ultraviolet spectral absorption of haemoglobins has been 

 studied in the high concentrations found in red blood cells : 

 Beer's Law is obeyed in the Soret band region up to 38-&per cent 

 haemoglobin concentration. The effects of denaturation and 

 drying on the ultraviolet spectral absorption of haemoglobins are 

 described and the recombination ofhaem andglobin is discussed. 

 These spectral absorption studies have been extended to intact 

 red blood cells. Continuous spectral light sources have been 

 used and the haemoglobin bands in the ultraviolet appear at 

 wavelengths identical with those in simple solution. The Soret 

 absorption band is present and of expected intensity and an 

 extra absorption band at 378 m \l has been observed in human 

 red cells. Red cells have been studied both as suspensions and 

 as individual cells using an ordinary glass train, and later a 

 reflecting microscope to project an image of the red cell on to 

 the spectrograph slit. Spectrograms of cross-sections of red 

 cells so obtained have been analyzed on a recording densitometer. 

 The differences between cytoplasmic and nuclear absorption in 

 frog red cells are shown. A difference in the ultraviolet spectral 

 absorption between human adult and foetal haemoglobin, which 

 does not extend to sheep or rat, has been observed. 



The study of the spectral absorption in the ultraviolet has considerable 

 value as a means of obtaining information about haemoglobins, and 

 I have set out here to discuss some of the potentialities of such studies 

 for illuminating the chemical behaviour of the haem-protein com- 

 pounds, and to show what can be learnt of their biological behaviour 

 when the study is extended to intact living material. Sir Joseph 

 Barcroft saw clearly the value of spectral observations, using them 

 whenever possible, and recent developments in equipment and ex- 

 pansion of the study of absorption spectra enable us to extend the 

 usefulness of such observations. 



The spectral absorption of the haem-proteins may be considered in 

 two distinct groups ; one, in the ultraviolet, is due to the aromatic 

 amino-acids of the protein and is dealt with towards the end of this 

 paper ; the other, a system of bands in the near ultraviolet and 



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