What is interstrand crosslinking?
Interstrand crosslinks (ICLs) are highly toxic DNA lesions that prevent transcription and replication by inhibiting DNA strand separation. Agents that induce ICLs were one of the earliest, and are still the most widely used, forms of chemotherapeutic drug.
What factors naturally cause DNA crosslinks?
Naturally occurring crosslinking agents include psoralens, mitomycin C, nitrous acids, etc.
What is DNA-protein crosslinks?
DNA-protein crosslinks (DPCs) are formed when a nucleotide residue on DNA forms a covalent bond with a protein (or a peptide, to form a DNA-peptide crosslink, DpC). Crosslinks are particularly hazardous, as they can effectively block gene transcription and DNA replication.
Is cisplatin a cross linking agent?
For instance, cisplatin has been reported to cross-link chromosomal proteins, including histones or cytokeratins, to DNA (8,9).
What is Intrastrand?
Adjective. intrastrand (not comparable) Within a strand, especially within a single strand of DNA.
What does Interstrand mean?
Definition of interstrand : existing or occurring between two or more strands (as of DNA) interstrand covalent inter-strand conductance in multistrand cables.
What causes DNA adducts?
The types of DNA adducts formed are dependent on the structures of the reactive chemicals, the nature of the electrophiles, and also on the ability of the compounds to intercalate with DNA, which may direct adduct formation to specific nucleophilic sites of the DNA bases (Fig. 3).
How does formaldehyde cross link proteins?
Formaldehyde crosslinking of biomolecules occurs in two steps. First, formaldehyde reacts with a relatively strong nucleophile, most commonly a lysine ε-amino group from a protein. This reaction forms a methylol intermediate that can lose water to yield a Schiff base (an imine).
What are the bonds between sugar and phosphate in DNA?
Explanation: The type of bond that holds the phosphate group to the sugar in DNA’s backbone is called a phosphodiester bond. Hydrogen bonds connect bases to one another and glycosidic bonds occur between deoxyribose groups and the base groups.
What is the mechanism of action of cisplatin?
The current accepted paradigm about cisplatin mechanism of action is that the drug induces its cytotoxic properties through binding to nuclear DNA and subsequent interference with normal transcription, and/or DNA replication mechanisms.
How does nitrogen mustard work?
The discovery of nitrogen mustard as an alkylating agent in 1942, opened a new era in the cancer chemotherapy. This valuable class of alkylating agent exerts its biological activity by binding to DNA, cross linking two strands, preventing DNA replication and ultimate cell death.
What is double strand break repair?
Double-strand DNA breaks are common events in eukaryotic cells, and there are two major pathways for repairing them: homologous recombination and nonhomologous DNA end joining (NHEJ). The diverse causes of DSBs result in a diverse chemistry of DNA ends that must be repaired.
What causes Depurination?
In cells, one of the main causes of depurination is the presence of endogenous metabolites undergoing chemical reactions. Apurinic sites in double-stranded DNA are efficiently repaired by portions of the base excision repair (BER) pathway.
Is Overstand a word?
Overstand definition To stand too strictly on the demands or conditions of.
What causes alkylation and leads to cross linking of proteins?
Initial DNA alkylation by mechlorethamine and chlorambucil leads to the formation of N7-guanine half mustards, which retain one of the chloroethyl groups (Scheme 1). These monoadducts can then react with a nucleophilic site within a neighboring protein, giving rise to DNA-protein cross-links.
What adduct means?
Definition of adduct (Entry 1 of 2) transitive verb. : to draw (something, such as a limb) toward or past the median axis of the body also : to bring together (similar parts) adduct the fingers. adduct. noun.
What is adduct in genetics?
DNA adduct is a piece of DNA covalently bond to a chemical (safrole, benzopyrenediol epoxide, acetaldehyde). This process could be the start of a cancerous cell. When a chemical binds to DNA, it gets damaged resulting in abnormal replication.
What’s the difference between phosphodiester bonds and hydrogen bonds?
The type of bond that holds the phosphate group to the sugar in DNA’s backbone is called a phosphodiester bond. Hydrogen bonds connect bases to one another and glycosidic bonds occur between deoxyribose groups and the base groups.
What is intrastrand and interstrand crosslinking?
Intrastrand and interstrand crosslinking of DNA In genetics, crosslinking of DNA occurs when various exogenous or endogenous agents react with two nucleotides of DNA, forming a covalent linkage between them. This crosslink can occur within the same strand (intrastrand) or between opposite strands of double-stranded DNA (interstrand).
Do interstrand G4 conformations serve a function similar to intrastrand quadruplexes?
Enrichments of interstrand and intrastrand PQS’s in the functional studies suggest that in DNA replication interstrand G4 conformations may have serve a function similar to intrastrand quadruplexes.
How common are Interstrand quadruplexes in human transcripts?
Searching for DS-PQS sites reveals potential interstrand quadruplexes in 52.5% of these sequences (p < 10−308; binomial); a total of 63.1% of human transcripts have at least one putative G-quadruplex of any type in their 1-kb upstream region.
What is the NMR structure of interstrand crosslinks?
NMR structure of these types of agents as interstrand crosslinks show that a 5′-GC adduct results in minor distortion to DNA, however a 5′-CG adduct destabilizes the helix and induces a bend and twist in the DNA.
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