Brazier: Nucleic Acids: on paper Flashcards
What are the two pyrimidines
Cytosine and thymine
What are the two purines
Adenine and guanine
How are nucleosides formed
Heterocyclic base attached to 5 membered sugar unit
What is the structure of A DNA and B DNA
A= C3’ endo
B= C2’ endo
How do drug molecules interact with DNA? (IMPORTANT)
- Intercalating Agents
- Topisomerase Poisons
- Alkylating Agents
- Chain Cutters
- Chain Terminators
What are intercalating agents?
Planar or heteroaromatic structures that fit between DNA base pairs held by van der waal forces
Can stabilise the oxygen charge on the DNA structure disrupting it
Give an example of a Intercalating agent?
Doxorubicin- interacts with DNA structure and intercalates planar tricyclic structure
Hinders normal action of topoisomerase II by keeping double strands broken
What is Topoisomerase II?
An enzyme that is found within DNA that cleaves it into two pieces- catalyses supercoiling
What are Topoisomerase II non intercalating drugs called?
Fluoroquinolones- interact with DNA enzyme complex and inhibit the biological functions
What are alkylating agents and give some examples?
Highly electrophilic molecule that will react with nucleophilic groups within the heterocyclic DNA bases
Form inter strand cross links and intrastrand ones
Examples: Cisplatin
What is an inter strand crosslink
Disrupts replication and transcription by hindering separation of strands
What is intra strand crosslink
Masks DNA structure from enzymes involved in replication and transcription
What is a chain cutter?
Drugs that cleave DNA and prevent enzyme DNA ligase from repairing the damage
Radical mecahnism resulting in oxidative cleavage of DNA structure
What is a chain terminator?
Drugs that interrupt the DNA replication sequence by binding midway during chain growth to terminate it
Act as false substrate
Need to write notes on RNA therapy
Antisense therapy
Duplex stability
Specificity
