Quantitative Analysis of Electron Diffraction Pattern and Image of Crotoxin Complex Thin Crystal
Crotoxin complex is the toxic principle in the venom of the South American rattlesnake, Crotalus durissus terrificus. This protein has two non-identical subunits and expresses its neurotoxicity via synergistic interaction. Unlike most of the neurotoxins isolated from snake venoms, this protein can have binding affinity to both post- and pre-synaptic membrane. We have reported earlier preliminary results of forming a thin crystal from this complex and of an electron diffraction pattern recorded to atomic resolution. The present paper is to discuss the space group symmetry of this protein crystal from the quantitative analysis of the electron diffraction intensities as well as of the low dose images.The crotoxin complex crystal was embedded in 1% glucose. The electron diffraction pattern and image were recorded on Kokak Industrex AA x-ray film with 0.1 e/Å2 and 2.5 e/Å2, respectively, at room temperature. These data were scanned with a Perkin-Elmer microdensitometer Model 1010. Figure 1 shows the original and the computer processed electron diffraction pattern.