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18 Cards in this Set
- Front
- Back
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Intercalating agents |
all contain a planar ring which slips between layers + disrupts the shape of helix Help in place via van der waals and ionic interactions with O- of phosphate on sugar backbone Prevents replication + transcription |
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Proflavine |
Intercalating agent which is a topical antibacterial |
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Examples of Intercalating agents |
Proflavine Quinine and chloroquinine Dactinomycin Doxorubicin Bleomycin |
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Quinine and chloroquinine |
intercalating agent used as anti-malarial agents |
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Dactinomycin |
Intercalating and topoisomerase poison Used as an anti-cancer drug extra binding to backbone via cyclic peptide group Intercalates minor groove Inhibits enzyme at major groove by blocking DNA DEPENDENT RNA POLYMERASE
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Other anti-cancer intercalating agents |
Doxorubicin- extra binding via NH3+ group Bleomycin- bithiazole ring system intercalates - also a chain cutter by and blocks DNA ligase from repairing damaged area |
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Topoisomerase poisons |
Stabalises complex between DNA + topoisomerase I irreversible double strand breaks during transcription contain lactone ring
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Anti-cancer topiosomerase poisons |
camptothecin etoposide teniposide |
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Anti-bacterial topiosomerase agents |
(quinolones) nalidixic acid ciprofloxacin ]] |
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Alkylating agents |
Contain highly electrophilic groups which covalent bond to nucleophilic groups in DNA prevent replication and transcription cross linking if two electrophilic groups present |
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Cross linking |
Interstrand and intrastrand crosslinking Normal base pairing- guanine prefers keta tautomer C-G
Adnormal base pairing - alkylated guanine prefers enol tautomer G-T |
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Anti-cancer alkalyting agents |
chlormethine- causes intrastrand + interstrand - Prevents replication also mono-alkalyation of guanine
Lomustine, carmuskine - also decompose to carbamoylating agent INTERSTRAND Busulfan- inter Dacarbazine- guanine alkalyation Mitomycinic - most toxic anti-cancer |
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Metallating agents |
cosplatin - ammonia molecules act as a ligand activated in cells with a low chloride ion conc BIND TO DNA IN REGIONS RICH IN GUANINE intrstrand links localised unwinding of DNA inhibits transcription |
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chain cutters |
bleomycin ( and Intercalating) used against skin cancer abstracts H from DNA to generate radicals
Calichemicin DNA diradical- reacts with O2 to cut chain |
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Chain terminators |
Azidothymidine pro-drug in HIV which inhibits viral enzyme Aciclovir- herpes and shingles
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Control gene transcription |
hairpin polyamides containing heterocyclic rings are capable of binding to the minor groove inhibit transcription
eg antibiotics |
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Antisense treatment |
short life time and poor absorption |
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micro RNA |
short segments of double stranded mRNA recognised by enzyme complex RISC to produce small interfering RNA which binds to complementary region of mRNA potential use in gene therapy |
