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Can human prolidase enzyme use different metals for full catalytic activity?
Marta E Alberto1, Monica Leopoldini, Nino Russo
1Dipartimento di Chimica and Centro di Calcolo ad Alte Prestazioni per Elaborazioni Parallele e Distribuite-Centro d'Eccellenza MIUR, Universita' della Calabria, I-87030 Arcavacata di Rende (CS), Italy.
Inorganic Chemistry
|March 24, 2011
Summary
This study explored the catalytic hydrolysis mechanism of the Gly-Pro substrate by bimetallic prolidase active site models. Cobalt-containing clusters showed slightly better performance in key reaction steps.
Area of Science:
- Biochemistry
- Computational Chemistry
- Enzyme Catalysis
Background:
- Prolidases are metalloenzymes requiring divalent cations (e.g., Zn2+, Mn2+, Co2+) for activity.
- Human prolidase can accommodate two different metal ions (Zn and Mn) while retaining partial activity.
- The precise catalytic mechanism and optimal metal composition of prolidase active sites remain incompletely understood.
Purpose of the Study:
- To investigate the catalytic hydrolysis mechanism of the Gly-Pro substrate using bimetallic prolidase active site model clusters.
- To identify the most efficient dimetallic metal center for prolidase-catalyzed reactions.
- To elucidate the roles of metal ions in different active site positions (Site 1 and Site 2).
Main Methods:
- Density Functional Theory (DF/B3LYP) calculations were employed to model the bimetallic active site.
- The hydrolysis of the Gly-Pro substrate by various metal clusters (Zn(II), Co(II), Mn(II)) was simulated.
- Hetero-bimetallic clusters (Mn-Zn) in different configurations (Mn1-Zn2, Zn1-Mn2) were analyzed.
Main Results:
- The rate-determining step for hydrolysis is the nucleophilic addition of hydroxide to the carbonyl carbon.
- Cobalt-containing clusters exhibited slightly superior performance in tetrahedral formation and decomposition due to enhanced charge transfer.
- Mixed Mn-Zn hetero-dimetallic clusters demonstrated catalytic activity, with a slight preference for the Mn1-Zn2 configuration.
Conclusions:
- The study provides fundamental insights into the prolidase catalytic mechanism.
- While no single metal showed a clear preference, cobalt clusters displayed favorable electronic properties.
- Hetero-bimetallic clusters, particularly Mn1-Zn2, are capable of catalyzing Gly-Pro hydrolysis, suggesting potential for mixed-metal active sites.
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