Which proteins are involved in unwinding DNA during replication?

The proteins involved in unwinding DNA during replication are topoisomerase and helicase.

Helicase is responsible for unwinding the double-stranded DNA by breaking the hydrogen bonds between the base pairs, effectively separating the two strands to create a replication fork. This unwinding is crucial because it allows other essential enzymes, like DNA polymerase, to access the template strands for replication.

Topoisomerase plays a supporting role in this process. As the DNA unwinds, it can become tightly coiled ahead of the replication fork. Topoisomerase acts to alleviate the torsional strain by cutting the DNA, allowing it to unwind further, and then resealing it. This action prevents supercoiling and ensures that the DNA strands remain accessible for replication.

Together, these two proteins facilitate the essential structure of DNA strands being separated so that replication can occur smoothly.