Mercoledì del PRIN n.8: Rocco Caliandro/Anna Giovanna Sciancalepore – Anna Maria Santoro

Biocatalytic units based on enzyme Crystals for efficient Continuous CO2 Conversion to formate – Bio4C

Dr. Rocco Caliandro and Dr. Anna Giovanna Sciancalepore

Global warming and climate change are directly related to Increased atmospheric CO2 levels, which are currently higher than ever  and continue to increase. Current strategies for CO2 reduction are mainly emission mitigation strategies and a new emergency has forcefully appeared on the international scene: the energy supply crisis triggered by the conflict in Ukraine. In this context, utilizing CO2 as a carbon source for production of high-in-demand chemicals represents a win-win strategy by both replenishing fossil-fuel processes and simultaneously assisting in mitigating CO2 accumulation and climate change.

In Bio4C we propose a revolutionary biomimetic system for effective and sustainable CO2 fixation into formate, an energy vector for biofuel or value-added chemicals generation. The overall goal is to develop a new bio-enabled material capable of effective conversion of CO2 to alternative fuels and chemicals, where the complex chemical processes carried out in bacteria or living cells are reproduced by a biomimetic artificial system composed of individual enzymes in their active form, closely packed to reach the highest possible density and embedded into bacterial-like coats able to preserve the enzymes in working conditions and allowing the entry of reagents (CO2, HCO3-), the exit of the product (HCOO-) and the exchange of electron-transfer mediators. Formate dehydrogenase (FDH) enzymes in the crystal form will be used as catalyst to convert CO2 into formate.

Our biomimetic catalytic unit represents a disrupting technology for effective and low energy demanding CO2 conversion, in the framework of the carbon capture and utilization strategy. It could be easily expanded upstream to implement a photosynthetic unit and downstream to implement multienzyme cascade reactions to convert formate into added-value chemicals.

Keywords

1. Enzyme crystals,
2. Biocatalytic unit,
3. CO₂ conversion

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Multifaced-peptidomimetics as proteasome modulators

Dr. Anna Maria Santoro

The rationale of the project is that is possible to mimic the orientation and the interactions of the key residues of a protein motif by varying the position and the nature of the substituents on a small-molecule scaffold. Accordingly, it is possible to develop small-molecule ligands as structural and functional mimics of protein motifs. Following this rationale, the projects aims at the identification of small non-peptidic molecules as allosteric modulators of the catalytic core particle (namely, 20S) of human proteasome. In particular, nature-inspired molecular scaffolds will be rationally modified in order to mimic the activating motifs of human 20S (h20S) regulatory proteins (RPs). The structural modifications will be guided by in silico studies and the experimental data will be used to optimize the design strategy in an iterative process. At first, the structures of all the RPs known to date will be investigated and small peptides corresponding to their 20S activating motif(s) will be synthesized and tested for their ability to interact with 20S and interfere with its catalytic activities. In particular, different 20S substrates will be designed and used in order to test the ability of the different RP motifs to selectively affect the 20S catalytic sites. At the same time, the molecular scaffold of natural compounds, such as silybins, able to mimic the HbYX consensus sequence of the activating motif of some RPs, or tyrosol-based curcumin mimics, able to mimic both α-helix based and β-sheet based protein motifs, will be rationally varied and the effect on 20S catalytic activities of the resulting series of compounds will be explored using the different substrates. The newly designed ligands will be studied either alone and in combination with RPs or RP-derived activating peptides. To reach our aim, a multidisciplinary approach will be applied including molecular modeling studies, chemical synthesis (both peptide and small ligands), NMR studies, and biochemical (cell-free and in-cell) investigation of the molecular interaction of the new ligands with 20S and its functional implications.

Keywords:

1. Proteasome
2. computer-aided drug design
3. natural compounds
4. allosteric modulators