Polymeric and dendrimeric pyridoxal enzyme mimics

Area of Science:

• * Supramolecular Chemistry
• * Organic Synthesis
• * Catalysis

Background:

• * Pyridoxal is a crucial cofactor for various enzymatic reactions.
• * Previous attempts to immobilize pyridoxal on polyethylenimine polymers resulted in rapid degradation.
• * Dendrimers offer a stable scaffold for functional molecules.

Purpose of the Study:

• * To synthesize and characterize stable pyridoxal-functionalized dendrimers.
• * To evaluate the catalytic efficiency of these dendrimers in amino acid racemization and decarboxylation.
• * To investigate the effect of dendrimer generation, terminal groups, and laurylation on catalytic activity.

Main Methods:

• * Synthesis of 12 poly(amidoamine) dendrimers (G1-G6) with NMe(2) or NHAc termini.
• * Covalent attachment of pyridoxal to the dendrimer core.
• * Incorporation of lauryl groups onto G5 pyridoxal dendrimers.
• * Kinetic studies of alpha-amino acid racemization and 2-amino-2-phenyl-propionic acid decarboxylation.

Main Results:

• * Dendrimeric pyridoxals are significantly more stable than pyridoxal-grafted polymers.
• * NMe(2)-terminated dendrimers accelerated alpha-amino acid racemization 50-100 times faster than simple pyridoxal.
• * NHAc-terminated dendrimers showed 3-5 times faster racemization.
• * Both dendrimer types exhibited 1-3 times faster decarboxylation rates.
• * Laurylated G5 dendrimers showed reduced racemization and decarboxylation rates.

Conclusions:

• * Pyridoxal dendrimers provide a stable and catalytically active platform.
• * Dendrimer structure, particularly terminal groups, significantly influences catalytic efficiency.
• * Laurylation negatively impacts the catalytic rates of pyridoxal dendrimers, contrary to previous findings.