The Isolation, Purification and Properties of Haemin a 



325 



(but not with toluene or chloroform) allowed an extensive extraction of haemin 

 a into acici acetone. Much other cellular material also extracted by the 

 pyridine-acid acetone mixture complicates further procedures. Using method 

 (1) above we have obtained porphyrin a from Torulopsis utilis with the ratio 

 of bands III/IV 2-24, but the probable losses associated with the necessary 

 use of pyridine suggest that this determination is only a useful approximation. 



SPECTROSCOPIC PROPERTIES OF HAEM a COMPOUNDS AND 

 HAEMOPROTEINS a 



We have begun a study of the absorption spectra of various haem a 

 compounds which may be useful as models for the cytochromes of group a. 

 Spectral data are given in Table I (ferric compounds) and Table 2 (ferrous 

 compounds) for compounds of haem a with pyridine, 4-methylimidazole, 

 cyanide, carbon monoxide, native human globin, human and ox serum 

 albumins, horse radish apoperoxidase, denatured human globin, denatured 

 serum albumins, as well as for the carbon monoxide compounds of the 

 haemoproteins and haemochromes. 



Table 1. Ferric haematin a compounds 



A in mn, in parentheses approximate fmsi* 



* Concentration was calculated making use of fniM 587 m/« of pyridine haemochrorae a in 20% pyridine-0-1 

 N NaOH-Na.,S.,04 (300). 



t Haematin a was extracted from its ethereal solution by 05 M borate buffer, or with 01 n NaOH followed 

 by adjustment of pH to 7-5. 



X No distinct maxima. 



Ferric Compounds 



Haematin a has a much greater affinity for hydroxyl ions than proto- 

 haematin. Thus, chlorohaemin a acquires the alkaline haematin a spectrum 



