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Exploring the structural and dynamic differences between human carnosinase I (CN1) and II (CN2)
Chompoonuch Tancharoen1, Borvornwat Tovivek1, Jitti Niramitranon2
1Department of Chemistry, Faculty of Science, Kasetsart University, Bangkok, Thailand.
Proteins
|January 13, 2023
Summary
Human carnosinases (CNs) are enzymes with two forms, CN1 and CN2. Differences in their active sites explain their varied substrate acceptance and catalytic efficiency, offering insights for treating diabetes and neurological disorders.
Area of Science:
- Biochemistry
- Enzymology
- Molecular Dynamics
Background:
- Human carnosinases (CNs) are metallopeptidase M20 family dipeptidases with two isoforms: CN1 (serum) and CN2 (tissue).
- CNs hydrolyze histidine-containing dipeptides, like carnosine; impaired CN function elevates carnosine, potentially reducing diabetes and neurological disorder risks.
- Limited data exists on CN2's function and structural/functional comparisons between CN1 and CN2.
Purpose of the Study:
- To comparatively investigate the structure and dynamics of human carnosinase 1 (CN1) and carnosinase 2 (CN2) using molecular dynamics (MD) simulations.
- To elucidate the molecular basis for differences in catalytic activity and substrate specificity between CN1 and CN2.
- To provide a microscopic understanding for developing CN inhibition strategies to increase carnosine levels.
Main Methods:
- Molecular dynamics (MD) simulations were used to analyze the structural dynamics of human CN1 and CN2.
- Comparative analysis of active site characteristics, including pocket size, environment, and metal ion interactions.
- Investigation of the role of specific structural elements, such as the L1 loop, in enzyme function.
Main Results:
- Differences in catalytic efficiency between CN1 and CN2 are attributed to variations in active site pocket size and microenvironment.
- CN2 exhibits broader substrate acceptance due to a wider binding pocket entrance.
- CN1 possesses a more electronegative active site entrance, enhanced wettability, and greater catalytic metal ion-pair stability, facilitating efficient water-mediated catalysis.
Conclusions:
- The distinct structural features of CN1 and CN2 directly influence their enzymatic activity and substrate specificity.
- Understanding these molecular differences provides a foundation for designing targeted CN inhibitors.
- Inhibition of CNs could lead to elevated carnosine levels, offering therapeutic potential for managing diabetes and neurological disorders.
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