152 



David L. Drabkin 



the frequency interval of 60, the graphic-mathematical analysis into com- 

 ponent bands fails to reproduce by their summation the observed absorption 

 in the regions v X 10^- = 160, 200, 280 and 320. These spectral regions do 

 have representative maxima in the absorption spectra of some of the chromo- 

 proteins (Table 2), and either two or more separate series would have to be 



150 



250 



Multiples of 40 = 4 » /? 5 



400 



350 



Fig. 7. The spectra of reduced and oxidized cytochrome c from horse heart, 

 pH 8-45. The molecular weight of reference was taken as 13,000 (0-43 % of iron). 

 The preparation had 0-412% of iron by Drabkin's o-phenanthroline method 

 (1941b). Reduction to ferrocytochrome c was by means of NaoSgOi for the data 

 to 380 m/ii and with palladium asbestos and hydrogen for the data in the ultra- 

 violet region beyond 380 m/<. To insure complete oxidation to ferricytochrome c 

 0-4 of an equivalent of ferricyanide was added to the 60 % oxidized preparation. 

 In the measurements this was balanced out by an equivalent amount ferrocyanide. 

 The abscissal scales indicate the postulated locations of bands in the equally 

 spaced, frequency distributed series (Drabkin, 1941a). 



assumed or a more appropriate single frequency spacing adopted. The 

 latter alternative was taken, and accordingly the 40 spacing was tested. This 

 spacing was preferred not only because of the locations of the observed 

 maxima, but also intuitively since it excluded both the a and (j bands. 



The supplemental Figs. 9 and 10 illustrate the analysis of the absorption 

 spectrum of cyanmethaemoglobin, taking Vq x 10~^ = 40. It may be seen 

 that the summation of the analytically resolved ten absorbing units or bands 

 agrees excellently with the observed spectrum, which can be expressed 

 mathematically (Drabkin, 1937) by 



sj, 



= ( 



kQ 



{x - [n X 40])- \ 



+ S(>'«,J^) 



(4) 



