Divergent or just different

The thesis of Henriëtte Rozeboom discusses the crystal structures of six different enzymes. These six enzymes belong to different protein families and utilize different catalytic mechanisms. Understanding their 3D structures is essential for understanding the molecular determinants of their function and may shed a light on how they have evolved. The first part describes the structural and mutational characterization of the catalytic A-module of the mannuronan C-5-epimerase AlgE4 from Azotobacter vinelandii, the second part discusses the crystal structure of α-1,4-glucan lyase, a unique glycoside hydrolase family member with a novel catalytic mechanism. The third part describes the crystal structure of quinone-dependent alcohol dehydrogenase from Pseudogluconobacter saccharoketogenes, a versatile dehydrogenase oxidizing alcohols and carbohydrates. The fourth part discusses the crystal structure of endo-xylogalacturonan hydrolase from Aspergillus tubingensis, an enzyme that specifically degrades xylogalacturonan. Finally, crystal structures of two Bacillus carboxylesterases with different enantioselectivities are discussed.