Ellipsoidal approximation, macromolecules

Conformation of the Macromolecule. In solution, macromolecules can have a wide variety of shapes or conformations. The simplest is the solid sphere or Einstein sphere. It is a round ball, impermeable to solvent. The ball may be stretched into a prolate ellipsoid like a football or flattened into an oblate ellipsoid like a flying saucer. Many soluble proteins have conformations that approximate ellipsoids. If a prolate ellipsoid is stretched enough, it becomes a rod. Certain virus macromolecules are rodlike. 

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