65 



the correctness of which we fail to question only because we have 

 seen it too often?- The ATP molecule has one C — N, one C — C, 

 and one C — O link (marked in Fig. 12 with arrows), which allow 



NHp 

 I 



N^^.,^ V H H OH OH OH 



III III 



^ ^ N-C-C-C-C-CHj-O-P-O-P-Q-P-OH 



^N / I I \ \ I! II II 



/ OH OH \ \ 



Fig. 12. ATP. 



a free rotation so that the molecule has a limited freedom to 

 change its shape and curl up. In fact, the outstretched linear form 

 of the molecule in Fig. 12 is an improbable one and the possibility 



" Possibly, chlorophyll also offers an example for such an influence of 

 visual pictures which inhibit our thinking in certain directions. Relations be- 

 tween chlorophyll and carotenes have been sought for a long time without 

 definite results. 



The Mg-porphyrin part of chlorophyll is reproduced in Fig. 13a, while 

 the chain of beta carotene is shown in Fig. l4a. The two structures seem to 



II 



CH *^,^3 CH3 



/\ /"\ /\ /\ /\ /\ 



CH C^ C C C — CHt-CH, CH, C OCX 



^ \ I I / 3 3 ^ \ / 



C=N N— G X C 



/ ^. / \ / \ 



HO, MQ .CH HC^ J:H 



C — N N C C C 



I II \ \ 



C^ yC .C — GH3 G C^ ^C — CH 



V ^/ \g^ ^c 



I I 



HG G«=0 



I 



COOGH3 



Fig. 13. a: Mg-porphyrin part of chlorophyll without the phytol side 

 chain, b: Same as "a" with Mg, N's, and longer side chains eliminated. 



3 



