Multivariate Statistical Analysis of 2D Protein Crystal Unit Cells

The purpose of this project was to enhance and interpret electron microscopy images of the Sodium Potassium ATPase, that is a cell membrane protein, and to develop a computer application that made all the needed steps in the analysis. The hypothesis that should be examined was that there was more than one possible conformation of protein unit cells in the crystal images of the ATPase, but it was not known how many conformations that could be expected to exist in the ATPase. The analysis consisted of three main steps, first a search for protein unit cells in the images, then a multivariate statistical analysis of the unit cell images and finally a clustering of the processed images. The computer application was successfully implemented and it was able to go through every step in the analysis. The final approach was a partly interactive implementation that suggested parameters for the user to approve or change. The analysis showed that there were three different conformations of the protein. The relative occurrence of the three conformations was about 5/4/1 according to the clustering. Multivariat statistisk analys av enhetsceller i 2D-proteinkristaller