730 



LIGHT AND LIFE 



300 400 



SOO 600 400 SOO 



600 



Fig. 3. Synthesis and bleaching of rhodopsin in solution, at 2'2.'^°C. pH 7. Left: 

 a niixttiic of ll-r/,s (neo-b) letinene and cattle opsin is incidjated in the dark, and 

 absorption spectra are recorded (1) at 0.3 min.. (2) at 2.5, (3) at 5, (4) at 10, 



(,')) at 18. (6) at 30, (7) at 60, (8) at 120. and (•)) at 180 minutes. The absorp- 

 tion band of W-cis retincne (X„,„x 380 ni^) falls regularly, as that of rhodopsin 



(Xn..ix 408 mfx) rises. Right: the rhodopsin formed at the left (1) is now exposed 

 to light of wa\clcngtlis longer than ,5.50 m/x for \arious intervals, and the absorption 

 spectra are recorded immediately afterward. I lie total irradiations were: (2) 5 min., 



(3) 10, (4) 15, (5) 30. and (6) 120 seconds. The residue was exposed for 45 seconds 

 longer to light of wavelengths longer than 1 10 m^; then spectrum (7) was recorded. 



(From VVald and lirown, 19). 



quickly stirred, and spectrum 1 immediately recorded. This shows the 

 absorption ])and ol neo-b retinene at about 380 irifx, and a small in- 

 flection near 500 niyu,, marking the first appearance of rhodopsin. This 

 mixture was now left in darkness, in place in the spectrophotometer, 



