Quaternary organization of subunits in the L‐leucine dehydrogenase from Bacillus cereus

Abstract
L‐Leucine dehydrogenase from Bacillus cereus was examined in the electron microscope. The quaternary structure reveals a molecule that is built up from 8 subunits, identical in mass, arranged in 2 layers which are oriented mainly in a staggered form. In each layer subunits are positioned at the vertices of a square, leaving free a central protein‐deficient region of 2.6 nm in diameter. The enzyme measures 11.1 nm in diagonal and 9.0 nm in edge length. Mean subunit diameter is 4.0 nm. The overall shape is a cube, slightly compressed, with 90% edge length in height.