AI Article Synopsis
- A DNA helicase from calf thymus, named DNA helicase F, was purified alongside replication protein A using various biochemical techniques, ultimately separating on FPLC Mono Q.
- Characterization showed DNA helicase F has a catalytic subunit of 72 kDa, can exist as both monomers and oligomers, and unwinds DNA in the 5' to 3' direction using all types of deoxyribonucleoside- and ribonucleosidetriphosphates as energy sources.
- DNA helicase F preferentially unwinds short DNA substrates and is enhanced by a single-stranded 3' tail, while replication protein A significantly extends its ability to unwind longer DNA strands up to 400 bases, suggesting
Article Abstract
A DNA helicase from calf thymus, called DNA helicase F, copurified with replication protein A through several steps of purification including DEAE-Sephacel, hydroxyapatite and single stranded DNA cellulose. It is finally separated from replication protein A on FPLC Mono Q where the DNA helicase elutes after replication protein A. Characterization of the DNA helicase F by affinity labeling with [alpha 32P]ATP indicated that the enzyme has a catalytic subunit of 72 kDa. Gel filtration experiments suggested that DNA helicase F can exist both in a monomeric and an oligomeric form. The enzyme unwinds DNA in the 5'-->3' direction in relation to the strand it binds. All eight deoxyribonucleoside- and ribonucleosidetriphosphates could serve as an energy source. Testing a variety of DNA/DNA substrates demonstrated that the DNA helicase F preferentially unwinds very short substrates and is slightly stimulated by a single stranded 3'-tail. However, replication protein A allowed the DNA helicase to unwind much longer DNA substrates of up to 400 bases, indicating that the copurification of replication protein A with the DNA helicase F might be of functional relevance.
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| http://www.ncbi.nlm.nih.gov/pmc/articles/PMC523632 | PMC |
| http://dx.doi.org/10.1093/nar/22.7.1128 | DOI Listing |
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