3 Compaction agent clarification of microbial lysates 4 Brad DeWalt

9 Recombinant proteins are often purified from microbial lysates containing high concentrations of nucleic acids. Pre-purification 10 steps such as nuclease addition or precipitation with polyethyleneimine or ammonium sulfate are normally required to reduce 11 viscosity and to eliminate competing polyanions before anion exchange chromatography. We report that small polycationic 12 compaction agents such as spermine selectively precipitate nucleic acids during or after Escherichia coli lysis, allowing DNA and 13 RNA to be pelleted with the insoluble cell debris. Analysis by spectrophotometry and protein assay confirmed a significant re14 duction in the concentration of nucleic acids present, with preservation of protein. Lysate viscosity is greatly reduced, facilitating 15 subsequent processing. We have used 5mM spermine to remove nucleic acids from E. coli lysate in the purification of a hexahis16 tidine-tagged HIV reverse transcriptase. 17 2002 Published by Elsevier Science (USA).