Analysis and Interpretation of Absorption Spectra of Haemin Chromoproteins 153 



The closeness of fit of the analytically derived spectrum with the experi- 

 mentally determined one is reflected by values of 3-29 for the mean of devia- 

 tions between them, 0-24 for the mean about which the deviations fall, 

 6-06 for S.D., and 0-47 for S.D. from 151 to 205 i5 x IQ-^ (Fig. 10). All the 

 absorption spectra of the haemin chromoproteins and their derivatives thus 

 far studied by the writer (a partial list of which is given in Table 2) can be 

 similarly analysed into their component bands, and equation (4) may be 

 regarded as generally applicable. 



(4) The dissection of the broad band of the spectrum of cyanmethaemo- 

 globin at wavelength 540 m// or v X 10-^ = 185 (Drabkin, 1937, 1938 and 

 Fig. 10) merits particular attention. The accurate establishment of the left 

 contour of this band reveals a very slight 'bump' in the vicinity of 570 m/< 

 (see curve 2 in Fig. 2 and the solid line in Fig. 10). There is also the appreciable 

 absorption in the regions of 630-600 and 500 m^w, the locations assigned in 

 the analysis to bands 4 and 5, which are represented by definite maxima in 

 some of the chromoprotein spectra (Table 2). These findings in themselves 



Table 2. Location of maxima (bands) in chromoprotein spectra, 

 postulated to belong to series « = (jt x 10"^)/(vo x 10~^) 



Vq X 10~^ is assumed = 40 (where n = 1). The values in brackets give the number 



n of the band in the series. The values in parentheses give locations of inflections 



(or bumps) in the absorption curve, as distinguished from obvious maxima. 



* With the Beckman DU spectrophotometer, measurements in this spectral location 

 are unreliable; with ferrocytochrome c a definite inflection in the curve at v x 10~^ = 446 

 was obtained with Hilger's Spekker photometer and medium quartz spectograph. 



t For the spectra of ferricytochrome c cyanide and cyanmetmyoglobin see Fig. 6. 



X For a maximum reported to be present in this location see the legend to Fig. 5. 



suggest the composite nature of this band. In the analysis, the order of 

 solution was band 4 first, then 5, then a, and finally /5. The need for a 

 /5 band and the locations of the centroids of a and /5 were consequences of 

 the analytical procedure. The centroids of the analytical a and /? bands are 

 respectively at i^ x 10"- = 179 (559 m//) and 187 (535 m/0 and k is larger 



