PhD forsvar: Heidi Asschenfeldt Ernst
Cand. scient. Heidi Asschenfeldt Ernst will give a public lecture on her thesis entitled: "Structural studies of enzymes in glycoside hydrolase family 31" followed by an oral defence. The defence is open to the public. The thesis was submitted in June 2008.Evaluation Committee:
- Professor Dr. Bauke W. Dijkstra, Department of Biophysical Chemistry, University of Groningen, Groningen, The Netherlands.
- Professor Anette Henriksen, Carlsberg Laboratoriet, Carlsberg Forskningscenter, Valby, Denmark.
- Associate Professor Ulla Christensen, (Chairman), Department of Chemistry, University of Copenhagen, Copenhagen, Denmark
Supervisors:
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Associate Professor Leila Lo Leggio, Department of Chemistry, University of Copenhagen, Copenhagen, Denmark.
- Professor Sine Larsen, Department of Chemistry, University of Copenhagen, Copenhagen, Denmark.
Abstract
The sequence-based family GH31 comprises enzymes that are very diverse in terms of substrate specificity and mechanism, including hydrolases, transglycosidases as well as glucan lyases. The majority of biochemically characterized GH31 enzymes are α-glucosidases which play essential roles in carbohydrate metabolism or in glycoprotein processing and quality control. A detailed understanding of the function of all these enzymes, on a molecular level, has been limited by the lack of structural information. This thesis addresses structural investigations of both hydrolytic and lytic GH31 enzymes. We have determined the crystal structure of the GH31 α-glucosidase MalA from Sulfolobus solfataricus, which provided the first three-dimensional model representing the major subgroup in GH31, embracing also the α-glucosidases from higher organisms. On the basis of the MalA structure, enzyme:carbohydrate complexes and comparison with other GH31 structures determined recently, the monomer fold, the active site architecture, substrate recognition and implications for substrate specificity are discussed.