qPCRi

qPCRi, also known as quantitative PCR inhibition, refers to a phenomenon where the efficiency of quantitative polymerase chain reaction (qPCR) is reduced or completely prevented. This inhibition can lead to inaccurate quantification of nucleic acid targets, impacting experimental results. Several factors can cause qPCR inhibition. These include the presence of inhibitors carried over from the sample preparation process, such as polysaccharides, humic acids, or certain salts found in environmental or plant samples. Inhibitors can also be introduced through reagents or consumables used in the experiment.

The mechanism of inhibition often involves interference with the enzymatic activity of the DNA polymerase. Inhibitors can bind to the polymerase, block its access to the DNA template, or interfere with the binding of primers or dNTPs. Additionally, some substances can chelate magnesium ions, which are essential cofactors for polymerase activity. The consequences of qPCR inhibition range from a decrease in the amplification efficiency, resulting in higher Cq (quantification cycle) values and underestimation of target amounts, to complete failure of amplification, where no signal is detected.

Detecting and mitigating qPCR inhibition is crucial for reliable results. Common strategies include optimizing sample purification methods to remove inhibitors, using alternative DNA extraction kits, or diluting the sample to reduce the concentration of inhibitory substances. Adding small amounts of known inhibitors to control reactions can also help assess the impact of potential inhibition on the experimental data. Specialized qPCR master mixes that are more resistant to common inhibitors are also available.