Ribonucleotide reductases and radical reactions

Area of Science:

• Biochemistry
• Enzymology
• Molecular Biology

Background:

• Ribonucleotide reductases (RNRs) are crucial enzymes catalyzing the conversion of ribonucleotides to deoxyribonucleotides, essential for DNA synthesis and repair.
• RNRs play a vital role in regulating cellular proliferation and are significant targets for antiproliferative drug development.
• All RNR classes uniquely depend on a protein radical cofactor for their catalytic activity.

Purpose of the Study:

• To elucidate the reactivity of protein radicals in different classes of Ribonucleotide reductases.
• To investigate the interactions of these radicals with natural substrates, enzyme inhibitors, and various reactive species.

Main Methods:

• Characterization of radical reactivity in Class I (tyrosyl/cysteinyl radical), Class II (cysteinyl radical), and Class III (glycyl radical) RNRs.
• Assays involving natural ribonucleotide substrates, substrate analogues, enzyme inhibitors, radical scavengers, nitric oxide, and superoxide radicals.

Main Results:

• Detailed description of the reactivity profiles of RNR protein radicals against a spectrum of molecules.
• Insights into how different classes of RNRs handle various substrates and inhibitory compounds.
• Understanding the influence of nitric oxide and superoxide radicals on RNR activity.

Conclusions:

• The study provides a comprehensive understanding of RNR radical chemistry and its modulation by different effectors.
• Findings contribute to the rational design of novel antiproliferative drugs targeting RNRs.
• This research deepens the knowledge of fundamental enzymatic mechanisms involving radical cofactors.