576 



Jerome J. Wolken 



680 



695 



w 



I I I I I \ I 



Wavelength m mp 



Fig. 



MICRONS ACROSS CHLOflOPLAST 



500 550 600 



Wavelength in imp) 



2 shews fine structure of the spectrum from 

 675-710 mn for a very young cultxrce. Chloro- 

 phyll a has absorption pealcs at 673, 683,and 

 695 mn. As the cells age, shifts in the ab- 

 sorption peaks to longer wavelengths occur. 

 Chlorophyll is not a free pigment molecule in 

 the chloroplast, but is camplexed to a pro- 

 tein or lipoprotein. The actively photosyn- 

 thesizing Euglena has chlorophyll uniformly 

 distributed throughout the chloroplast as il- 

 lustrated in Fig. 3. 



Coupled vith the chlorophyll-protein of 

 the chloroplast is a cytochrome system. Two 

 spectrally different cytochrome-c types were 

 isolated and characterized from phot ©synthe- 

 sizing and non-phot OS ynthe sizing Euglena . 

 These are referred to as cytochrome-552 and 

 cytochr ome -556 w). CytoclTrome-552 has ab- 

 sorption peaks in the reduced state at 552, 

 523, and 4l6 mnj cytochrome-556 has absorp- 

 tion peaks in the reduced state at 556, 525, 

 and i|-21 ra|a(l). Cytochrome-556 -v/as also ex- 

 tracted from substrains of Iffi, heat-bleached 

 and SM, streptomycin-bleached Euglena cells 

 with absorption spectra identical, to those 

 extracted from dark-grovm Euglena ''"^. 



When dark-grown Euglena are re-adapted to 

 light, diAring the first 24 hrs., while the 

 cells are actively synthesizing chlorophyll, 

 only cytochrome-556 can be isolated; however. 

 Fig. 3 after UQ hrs., only cytochrome-552 is found. 

 The apparent shift from cytochrome-556 to cy- 



700 



