3H 



J. A. BERGERON AND R. C. FULLER 



changes in the absorption spectrum (Fig. 6). The sedimentation diagram 

 of the "cleared" extract reveals three major components with sedimenta- 

 tion coefficients of about 5, 30, and 50 Svedberg units (S) respectively. 

 The colour due to the photosynthetic pigments is related to the most 

 rapidly sedimenting component. It is easy to eliminate the slowest com- 

 ponent (5 S) by repetitive centrifugation but it is rather difficult to elimin- 



200 



300 



400 



500 600 



700 



800 



900 



Fig. 6. Record of the changes in the sedimentation diagram (Spinco Model E) 

 and absorption spectrum (Gary Model 14) during the isolation of the pigmented 

 component. There are three major components in the crude extract. The colour 

 due to the photosynthetic pigments is associated with the component (50 S) which 

 sediments the most rapidly. The absorption at 260 m// due to nucleic acid is greatly 

 reduced as the slower components are eliminated. 



ate completely the 30 S component under conditions which recover the 

 pigmented component (50 S) in high yield. The progressive elimination of 

 the two slower components is reflected in the absorption spectrum by the 

 drastic reduction in nucleic acid absorption at 260 m/i. 



If a crude extract is placed upon a linear sucrose gradient (10% to 

 50%) and centrifuged for several hours in a swinging bucket head at 

 156000 g two coloured zones develop, the "green "zone with a sharply 

 defined leading edge is followed by a less distinct "yellow" zone. Com- 



