Fill in the Blanks Chemotherapy Drugs (modes of action) IOnline version Learning objectives: - Understand the relationship between DNA structure and modes of intercalation - Have an insight into the therapeutic mode of action of Doxorubicin - Know the sites of alkylation in DNA - Describe DNA alkylation with chlorambucil and cyclophosphamide by Zainab Nabeel 1 cytosine Electrostatic bacteria Doxorubicin adenine planar Understand the relationship between DNA structure and modes of intercalation Intercalating agents : Intercalating drugs contain a aromatic or hetero - aromatic ring system which can fit into the double helix of DNA and distort its structure . Once bound , the drug can inhibit the enzymes involved in replication and transcription processes . Anthracyclines are a set of naturally occurring antibiotics isolated from which have anti - cancer properties with a mode of action involving DNA intercalation . Have an insight into the therapeutic mode of action of Doxorubicin is an Anthracycline which intercalates DNA . During replication Doxorubicin interferes with the activity of the DNA - topoisomerase II complex which cuts and reseals DNA to relieve tension during uncoiling . DNA often remains cut . This prevents DNA replication and prevents cell replication . It usually causes cell death . Doxorubicin : - Isolated from streptomyces peucetius in1967 - One of the most effective anti - cancer agents , used to treat a broad spectrum of solid tumors - Intercalates into DNA and acts as a topoisomerase II ( an enzyme involved in DNA replication process ) poison as it stabilizes the complex formed between DNA and topoisomerase II - Excessive number of stabilized DNA - enzyme complexes triggers apoptosis Doxorubicin Bound to DNA : Inserts at GC and CG base pairs causing a 'buckle' - prevent van der Waals contacts between NBs . - distort DNA structure Stabilized by - interaction ( - NH3 + amino sugar with phosphate ) - H - bonding - Aromatic pi - pi interactions Know the sites of alkylation in DNA N7 of guanine , N1 , N3 , and N7 of , and N3 of . Describe DNA alkylation with chlorambucil and cyclophosphamide It is explained somewhere else
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