Table 1.

Purification of complementing activity from baboon kidney extracta

StepTotal protein (mg)Total activityb (U)Sp act (U/mg)Purification (fold)Recovery (%)
1. WCE95215,00115.71100
2. 15 to 30% AMS11512,3401076.882
3. Sephacryl S300549,60017811.364
4. RNA affinity0.00025c 5502,200,000140,1273.6
  • a Complementing activity was purified from whole-cell extracts (WCE) obtained from 20 g of baboon kidney by precipitation with 15 to 30% ammonium sulfate (AMS) and gel filtration on Sephacryl S300. For RNA affinity chromatography, proteins were precleared with a mutant apo-B RNA column. The unbound fraction was incubated with the wild-type RNA affinity column, and the bound proteins were eluted with 0.5 M NaCl.

  • b One unit is defined as the amount of complementing activity that edits 1 fmol of apo-B RNA/h in the presence of recombinant apobec-1.

  • c Because of the low yield, the total protein in this fraction was estimated by silver staining in comparison with known standards.