Topoisomerase I
Topoisomerase I (pronunciation: toh-poh-ih-soh-MER-ayz one) is an enzyme that plays a crucial role in the process of DNA replication and transcription.
Etymology
The term "Topoisomerase I" is derived from the Greek words "topos" meaning place and "isomerase" from the Greek "isos" meaning equal and "meros" meaning part. This refers to the enzyme's function in maintaining the correct topological state of DNA during replication.
Function
Topoisomerase I is a type of enzyme that alters the supercoiled form of a DNA molecule. This is a vital function as it helps to reduce the tension in the DNA strand that is created during the replication process. It achieves this by creating a break in one strand of the DNA molecule, allowing it to unwind and then resealing the break.
Related Terms
- DNA: Deoxyribonucleic acid, the molecule that carries genetic information in all living organisms.
- Enzyme: A protein that acts as a biological catalyst to speed up chemical reactions in cells.
- DNA replication: The process by which a double-stranded DNA molecule is copied to produce two identical DNA molecules.
- Transcription (genetics): The first step of gene expression, where a particular segment of DNA is copied into RNA by the enzyme RNA polymerase.
Clinical Significance
Inhibitors of Topoisomerase I, such as Topotecan and Irinotecan, are used as chemotherapy agents in the treatment of various types of cancer. They work by preventing the re-ligation step of the enzymatic cycle which leads to DNA damage and ultimately, cell death.
External links
- Medical encyclopedia article on Topoisomerase I
- Wikipedia's article - Topoisomerase I
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