Electron microscopy of human erythrocyte catalase: new two-dimensional crystal forms

Using the mica-spreading "negative staining-carbon film" procedure, human erythrocyte catalase has been shown to create a number of different periodic or crystalline two-dimensional (2-D) arrays which differ in the arrangement of molecules in the repeating units and the lattice type. Digital image processing has been performed with a 2-D array which contains regularly arranged "undulating" rows of molecules and also with a 2-D crystal form, exhibiting pgg (p22(1)2(1)) symmetry and lattice parameters of a = 12.7 nm, b = 44 nm, and gamma = 92 degrees. The data are compared with our previous analysis of a different human erythrocyte catalase 2-D crystal, and the effect of partial-depth negative staining occurring in all the various 2-D forms is discussed.