Final answer:
In the Fenton reaction for DNA cleavage, EDTA chelates and stabilizes Fe3+, while ascorbate reduces it to Fe2+ to facilitate the generation of hydroxyl radicals for DNA strand cleavage.
Step-by-step explanation:
In the standard recipe for DNA cleavage by the Fenton reaction, which includes Fe3+/EDTA/Ascorbate/HOOH, EDTA and ascorbate play vital roles. EDTA is used as a chelating agent to sequester metal ions. Specifically, the EDTA ion wraps up the metal ion, in this case Fe3+, to prevent undesired reactions by utilizing its multiple coordinate bonds. This stabilizes the iron ion so that it can effectively participate in the catalytic process.
On the other hand, ascorbate acts as a reducing agent. It reduces Fe3+ to Fe2+, which then reacts with hydrogen peroxide (HOOH). This reduction step is important because the Fenton reaction requires Fe2+ for the generation of hydroxyl radicals (•OH), which are the species responsible for cleaving the DNA. Therefore, ascorbate is crucial for maintaining the iron in its active, reduced state.
SUMUP of the Final Answer:
- EDTA serves as a chelating agent, stabilizing Fe3+ by surrounding it completely.
- Ascorbate functions as a reducing agent, converting Fe3+ to Fe2+, a necessary step for the Fenton reaction to proceed.