CHLOROPHYLL FORMATION 



405 



The absorption curves of protochlorophyll from pumpkin seed coats 

 dissolved in ether and in pyridine have been determined by Krasnovskii 

 and Voinovskaya (1949). The similarity of the curves for ether solu- 

 tions of protochlorophyll from leaves and pumpkin seed coats is remark- 

 able (Fig. 7-5). 



For comparison, the absorption spectra of chlorophylls a and b dis- 



solved in ether are given in Fig. 7-6. 

 on chromatographically purified pig- 

 ments, and the specific absorption 

 coefficients calculated from the mag- 

 nesium content of the solutions by 

 converting them to actual concentra- 

 tions of chlorophyll. The values 

 agree reasonably well with those pub- 

 lished by Comar and Zscheile (1942) 

 and Mackinney (1941) (see also 

 Zscheile et al., 1942). 



Absorption Spectrum of Protopheo- 

 phytin. In connection with studies 

 on protochlorophyll, the absorption 

 spectrum of protopheophytin has fre- 

 quently been of use. Absorption 

 curves of protopheophytin derived 

 from protochlorophyll have been 

 measured by Seybold (1948-1949) and 

 by Koski (1949). The absorption 

 curve for "synthetic" vinylpheopor- 

 phyrin-as monomethyl ester in dioxane 

 has been published by Granick (1950). 

 Both Koski and Granick determined 



Xhese measurements were made 



400 500 600 



WAVE LENGTH . a\fX 



700 



Fig. 7-7. Comparison of protopheo- 

 phytin values calculated from the ab- 

 sorption measurements of Granick 

 (1950) on "synthetic" vinylpheo- 

 porphyrin-as methyl ester in dio.xane 

 with the absorption spectrum in ether 

 of protopheophytin from protochloro- 

 phyll out of barley leaves. (Koski, 

 1949.) 



the absolute values of the specific 



absorption coefficients. A comparison of these two measurements is 

 given in Fig. 7-7. The similarity of the values gives confirmatory 

 evidence for the identity of the basic structures of the substances derived 

 from chlorophyll a and from protochlorophyll. 



The positions of the absorption maxima and the corresponding specific 

 absorption coefficients for protopheophytin in ether solution are as follows 

 (cf. Koski and Smith, 1948) : 



Absorption-maxima wave lengths, mju 638 585 565 524 417 



Specific absorption coefficients 2.5 17.3 25.1 11.7 256.6 



Fluorescence of Protochlorophyll. Mikosch and Stohr (1880) were prob- 

 ably the first to recognize the orange fluorescence of protochlorophyll. 

 Since then, the fluorescence of this pigment has been measured by several 



