224 FREDERICK G. E. PAUTARD 



Although experiments on flagellar protein and actomyosin (Pau- 

 tard, 1959) suggest that biological contraction may be due to a proton 

 transfer mechanism (proposed also by Goodall, 1958), there are con- 

 flicting views on changes of pH in muscle during contraction. Some 

 measurements suggest very small shifts of pH (Caldwell, 1958); 

 others suggest appreciable values (Disteche, 1960). Since the term 

 "pH" is meaningless when applied to a macromolecule with as many 

 polar groups as a protein, it may be advantageous to think in terms 

 of transfer of charges across polypeptide chains, in which case the 

 flagellum may derive energy for movement without the actual trans- 

 port of electrolytes at all. This is particularly true of bacterial flagella, 

 where no enzyme activity or substrate has been detected (Weibull, 

 1948; Barlow and Blum, 1952) and there is no alternative but to 

 consider contraction in terms of physics alone. 



A Possible Universal Molecular Basis for Movement 



The flagella that have been studied appear to be largely composed 

 of unstable protein or proteins, possibly of a globular type. It may be 

 that these proteins are unconnected with contraction, but additional 

 physical evidence, from studies of both flagella and muscle, suggests 

 that perhaps the globular proteins, or at least certain types of globu- 

 lar proteins, may be the prime movers in biological contraction. The 

 evidence in support of this is as follows. 



Whatever the morphological arrangements in muscles, flagella, and 

 reconstituted gels, there is no doubt that the proteins involved are 

 members of the k-m-e-f group and satisfy Astbury's (1947a) concept 

 of contraction as part of a much wider plan throughout nature. The 

 contractile event, one way or another, is vested in these proteins, and 

 we need look no farther. In muscle, the problem is to decide whether 

 both actin and myosin are essential for contraction in the molecular 

 sense. In the past, a great deal of emphasis has been placed on the 

 myosin partner, partly because of the way in which "myosin" pre- 

 ceded actin in the literature and partly because intramolecular con- 

 figurational changes have been actually demonstrated with the a-pro- 

 teins. Thus, the appearance of the strong cross-/? photograph in the 

 diffraction diagrams of heated muscle has been considered as a trans- 

 formation of the myosin during supercontraction, while experiments 

 demonstrating a "melting" of the crystalline phases during physio- 



