Electron microscopic and biochemical characterization of fraction I protein.

Electron micrographbs of high resolution have been obtained from fraction I protein of Chinese cabbage leaves. The protein, which has ribulose-1,5-diphosphate carboxylase activitY, appear to be a cube swth edge of about 120 angstroms. Substrtucture canl be seen in individual particles, conlsistent with a model having 24 subunits, the number prescribed by the available physical and chlemical data.