Universiteit Leiden

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A new method to reconstruct the structure from crystal images

Promotor: J.P. Abrahams, Co-promotor: T. Grüne

Yao-Wang Li
03 mei 2017
Thesis in Leiden Repository

Biological molecules, especially the proteins, have a special and important function. We study their structure to understand their functions, and further make application, like the medical research. The routine method is diffraction, but not work for molecules which cannot grow into crystal and molecules which their crystal are too small. Cryo-EM technique provides another way to solve their structures through their images, it does not need crystals. Meanwhile, electron diffraction can work small crystals (micro- and nano-crystals) after the sample preparation was improved. Hence, we try to build a method that can restore the structure from the crystal’s image. We collect images of protein nano-crystal, and these images were processed to enhance their contrast. The key step is to find the orientations of these images in the procedure of reconstruction, therefore, we create a method that calculates these orientations. Nano-crystals, which cannot be used in diffraction method, then can be used in this method.