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Structural comparison of Ntn-hydrolases.
1Department of Chemistry, University of Joensuu, Finland. Carita.Oinonen@joensuu.fi
Protein Science : a Publication of the Protein Society
|February 24, 2001
Summary
N-terminal nucleophile (Ntn)-hydrolases share a conserved core structure despite lacking sequence homology. Key conserved regions and catalytic machinery suggest similar mechanisms, though substrate binding varies.
Area of Science:
- Biochemistry
- Structural Biology
- Enzymology
Background:
- N-terminal nucleophile (Ntn)-hydrolases are a recently characterized enzyme superfamily.
- These enzymes feature an N-terminal catalytic nucleophile and undergo autocatalytic activation.
- They are characterized by their ability to cleave amide bonds.
Purpose of the Study:
- To compare the detailed structures of four Ntn-hydrolase enzymes.
- To identify conserved structural features and variations within the Ntn-hydrolase superfamily.
- To elucidate the structural basis for their catalytic mechanisms.
Main Methods:
- Comparative structural analysis of four Ntn-hydrolase enzymes.
- Identification and analysis of conserved secondary structure units.
- Examination of core structure, beta-sheet packing angles, and catalytic machinery.
Main Results:
- Despite absent sequence homology, Ntn-hydrolases share a common alphabeta betaalpha-core structure.
- Central beta-sheets exhibit varying packing angles (5-35 degrees).
- Eight conserved secondary structure units were identified, with five being crucial for structure and function.
- Catalytic machinery is similarly located, suggesting conserved mechanisms, but substrate binding and oxyanion holes show partial differences.
Conclusions:
- Ntn-hydrolases possess a conserved structural fold and catalytic machinery, implying similar enzymatic mechanisms.
- Structural variations in substrate binding sites and oxyanion holes contribute to functional diversity.
- Understanding these structural-functional relationships is key for Ntn-hydrolase research.