Comparison of DNA extraction using proteinase K and extraction kit: analysis of the quality of the genetic material

ABSTRACT INTRODUCTION: Deoxyribonucleic acid (DNA) is the raw material for genetic studies, and therefore laboratory techniques are developed to obtain it with appropriate concentration and integrity. OBJECTIVE: To compare two methods of DNA extraction regarding sample concentration and integrity. METHODS: DNA was extracted from the tail end (2 mm long) of mice, stored at -20ºC. The proteinase K method (PKM) and the Kappa Express Extract® kit were used for extraction. The concentrations and ratios 260/280 and 260/230 were determined by spectrophotometry. DNA integrity was checked on 2% agarose gel with ethidium bromide. For the final test of the extracted samples, a multiplex polymerase chain reaction (PCR) was performed, with primers for the Large gene. RESULTS: Samples extracted by the PKM presented mean concentration value of 59.4 ± 18.5 ng/µl (260/280 = 1.74 ± 0.04 and 260/230 + 1.85 ± 0.14) and the samples extracted by the commercial kit presented mean concentration value of 178.8 ± 42.0 ng/µl (260/280 = 1.09 ± 0.04 and 260/230 = 0.62 ± 0.66). PCR amplified the Large gene in the DNA extracted, regardless of the methodology used. CONCLUSION: Both methodologies studied can be used, and the PKM is cheap but a time-consuming method, while the commercial kit is more expensive, however DNA extraction is faster.