73 



cule, the pentose which has to connect the adenine and the phos- 

 phates in such a way that they come together exactly in the right 

 position. A hexose would not do. But this may not be all there is 

 to it. Nature often kills more than one bird with the same stone. 

 It may be worth noting in this connection that the United States 

 Patent Office has granted two patents for the hardening of gelatine 

 by pentose, a reaction not shared by hexose.^ This suggests that the 

 ribose can enter into an intimate reaction with the protein which 

 may very well play an important role in the "activation" of ATP. 



One last remark may be made about Ca. It greatly promotes 

 the "ATP-ase activity" without promoting contraction or analo- 

 gous reactions, such as "superprecipitation." It even inhibits them. 

 One tentative explanation which may be given for this behavior 

 could be that Ca, similarly to Mg, forms chelates and weakens the 

 ~P but is unable to transmit its energy to the purine, owing to the 

 great differences in the energy terms of Ca and N. Accordingly, 

 Ca is also unable to promote the oxidoreduction between 1,2-naph- 

 thoquinone and o-phenylenediamine. 



In Chapter 12 we will return once more to a possible additional 

 role of pentose. 



While reading the proof sheets of this book my attention was 

 kindly called to a paper of B. H. Levendahl and T. W. James 

 [B'wchJm. et Biophys. Acta 21, 298, 1956). Its summary may be 

 quoted without comment: "The rotatory dispersion of adenine, 

 adenosine, AMP, ADP, and ATP have been determined. The data 

 have been interpreted to show that the ATP molecule is folded 

 back on itself in such a manner that bonding is permitted between 

 the last two phosphate groups and the amino group of adenine. 

 This stabilized structure is then proposed as necessary for the ac- 

 tion of ATP. Parallel 'ATP-like' action of CTP and UTP and 

 other triphosphonucleotides could be explained by possession of a 

 similar configuration." 



*USA Patent No. 2,059,817 (Nov. 3, 1956) and Patent No. 2,180335 

 (Nov. 21, 1939), the first granted to the Eastman Kodak Co., Jersey Cit>'. 

 N.J., the second to the Agfa Ansco Corporation, Binghamton, N.Y. 



