BIOLOGICAL SYSTEMS
A STUDY OF THE SELF-ASSOCIATION OF MYOSIN BY INTENSITY FLUCTUATION SPECTROSCOPY

Résumé
Nous avons mesuré le spectre, l'intensité, et le facteur de la forme de la lumière diffusée quasi élastiquement par une solution de myosine, la protéine de la contraction. Ces résultats expérimentaux sont expliqués en utilisant une forme générale de la relation d'Einstein pour le coefficient de diffusion. Nous concluons que la myosine est dans un équilibre monomère-dimère en solution et aussi que les deux monomères sont en association parallèle et non en association antiparallèle.

Abstract
The self-association of myosin has been reported by Godfrey and Harrington (1970). We, Herbert (1970) and Herbert and Carlson (1971) have studied myosin self-association using recently developed techniques of scattered light spectroscopy. The theoretical and experimental details of these studies have been published elsewhere by Herbert (1970) and Herbert and Carlson (1971). In this paper we wish to call attention to a generalization of the Einstein relation for the microscopic translational diffusion constant that we have developed and found useful in interpreting spectral data obtained from highly non-ideal solutions of macromolecules such as myosin and other biological macromolecules. Further, we have found that if in addition to spectral data one measures both the absolute intensity and the angular distribution of the scattered light a more comprehensive description of the properties of the macromolecular solution is possible. And finally we have extended the analysis of our original data in a way that allows us to draw some conclusions about the configuration of the two monomeric units in the dimer.