Final answer:
The Klenow fragment of DNA polymerase I is not used for digesting away protruding 3'-overhangs because it lacks 5'→3' exonuclease activity, which is required for that function. It's highly utilized in DNA sequencing, nick translation, and filling-in DNA at recessed 3'-ends.
Step-by-step explanation:
The DNA polymerase I Klenow fragment is not used for digesting away protruding 3'-overhangs. The Klenow fragment of DNA polymerase I retains both polymerization activity and 3'→5' exonuclease proofreading activity but lacks the 5'→3' exonuclease activity that is responsible for removing RNA primer nucleotides including those at the ends of Okazaki fragments in DNA replication. Instead, it is commonly used in DNA sequencing, nick translation, and filling-in DNA at recessed 3'-ends to create blunt ends.
DNA polymerase I's full enzyme has the ability to remove RNA primers from the Okazaki fragments due to its 5'→3' exonuclease activity and replaces them with DNA nucleotides, while DNA ligase seals the ends of the new DNA segment. However, removal of protruding 3'-overhangs requires an enzyme with 3'→5' exonuclease activity, which the Klenow fragment does not possess. The primary role of the Klenow fragment in DNA sequencing involves adding nucleotides and terminating the DNA strand extension by incorporating dideoxynucleotide analogs, allowing the determination of the DNA sequence.