Chemistry and Biology of Proteins - F. Haurowitz 1953

Size and Shape of Protein Molecules
Electron Microscopy of Proteins

This method provides direct information regarding Molecular dimensions. At the current level of technology, Electron Cell/15.html">Microscopy is limited to determining the size of only the largest protein molecules, primarily virus particles. Particularly sharp images can be obtained by preliminary shadowing of the particles through unidirectional evaporation of gold or chromium. The metal deposits on one side of the particle, creating a shadow effect and imparting depth to the resulting image [72]. The first electron micrographs were produced by von Ardenne [73], who found that the molecular diameter of hemocyanin is 220 Å. Each hemocyanin particle apparently represents a bundle of four smaller subunits [74]. Edestin forms approximately spherical particles with a diameter of about 70 Å [75]. Myosin, a Muscle protein, consists of filaments 50–100 Å wide and several thousand angstroms long [76]. The cross-sectional diameter of tobacco mosaic virus particles is 150 Å, and the length of the molecule is 2,800 Å [77].