α-β Intramolecular Transformation of Myosin

Abstract

SHORTLY after the discovery and investigation by the methods of X-ray analysis¹of the long-range elastic, intramolecular transformation which takes place when the fibre-substance (keratin) of hair is stretched, the possibility emerged that the elastic mechanism of muscle is similar at least in principle to that of hair². There is a remarkable likeness between the X-ray photograph of washed and dried muscle and that of unstretched hair (α-keratin), and there are, moreover, certain striking analogies between their respective elastic properties. Recently, the X-ray and elastic comparison between muscle and hair has been set out in detail³, and once more the suggestion was made that the normal molecular configuration of the muscle protein myosin—first shown by Boehm and Weber⁴ to give, when oriented, an X-ray photograph resembling^* that of muscle itself—is that of a folded polypeptide chain system like that of α-keratin, which it should be possible, by extension under appropriate conditions, to transform into a fully-ex tended system like that of β-keratin (stretched hair). The present writers tried to bring about this transformation two years ago by experiments on the sartorius muscle of the frog, but without success².