Question

The klenow fragment is a large protein fragment produced when dna polymerase i from

e. coli is enzymatically cleaved by the protease subtilisin. it retains the dna polymerase activity and the proofreading activity, but loses its other activity. which one is it

Answer 1

The Klenow fragment is a large protein fragment produced when DNA polymerase I from E. coli is enzymaticallycleaved by the protease subtilisin. First reported in 1970,[1] it retains the 5' → 3' polymerase activity and the 3’ → 5’ exonuclease activity for removal of precoding nucleotides and proofreading, but loses its 5' → 3' exonuclease activity.

The other smaller fragment formed when DNA polymerase I from E. coli is cleaved by subtilisin retains the 5' → 3' exonuclease activity but does not have the other two activities exhibited by the Klenow fragment (i.e. 5' → 3' polymerase activity, and 3' → 5' exonuclease activity).