i was cloned the lysin gene of bacteriophage in the pGEX 4t1 vector and transformed them in the BL21 Competent cell. competent cell was transformed and upon induction they are showing the induction of desired band of recombinant protein size in the sds page. but when for their purification purpose i was breaking the cell by using three times freeze thaw cycle at -80degree Celsius. after freeze thaw cycle i observed that my lysate become two viscous that it cannot got separated into supernant and pellet after centrifugation at 13000 rpm for 20minutes
please give me the reason why this happen with my clone?
When the cells break open, the DNA is released. The chromosomal DNA, being a very large molecule, causes the viscosity. To break up the DNA into smaller pieces, you can add some DNase + Mg2+.