A rapid technique for estimating DNA binding, used to evaluate 1-nitropyrene adduct formation

Area of Science:

• Biochemistry
• Toxicology
• Cell Biology

Background:

• Assessing the binding of xenobiotics to cellular macromolecules like DNA and protein is vital for understanding toxicity.
• Existing methods for quantifying such binding can be complex and time-consuming.

Purpose of the Study:

• To develop and validate a simple, rapid procedure for estimating the binding of radiolabeled substances to DNA and protein.
• To apply this method to quantify DNA and RNA adducts formed from 1-nitro[14C]pyrene in rabbit alveolar macrophages.

Main Methods:

• Protein extraction from lysed rabbit alveolar macrophages using chloroform:iso-amyl-alcohol:phenol.
• Precipitation of nucleic acids followed by hydrolysis with protease and NaOH to remove residual protein and RNA.
• Quantification of bound radioactivity via DNA precipitation onto glass fiber filters.

Main Results:

• The developed procedure effectively quantifies bound radioactivity.
• Demonstrated the binding of 14C to endogenous protein and DNA in rabbit alveolar macrophages incubated with 1-nitro[14C]pyrene.
• Successfully used radiolabeled protein (3H-leucine) and DNA/RNA adducts (from 1-nitro[14C]pyrene) to define the assay.

Conclusions:

• A straightforward and efficient method for quantifying radiolabeled material bound to DNA and protein has been established.
• This method is suitable for analyzing DNA and protein adducts, contributing to toxicological risk assessment.
• The procedure is applicable to complex biological samples like those from macrophages.