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To carry out gene expression, a cell must control the coiling and uncoiling of DNA around histones.This is accomplished with the assistance of histone acetyl transferases (HAT), which acetylate the lysine residues in core histones leading to a less compact and more transcriptionally active euchromatin, and, on the converse, the actions of histone deacetylases (HDAC), which remove the acetyl ...
[5] [6] These molecules can be composed of single-stranded DNA or RNA and are generally 13–25 nucleotides long. [6] [7] The antisense oligonucleotides can affect gene expression in two ways: by using an RNase H-dependent mechanism or by using a steric blocking mechanism.
Anti-metabolites also affect RNA synthesis. However, because thymidine is used in DNA but not in RNA (where uracil is used instead), inhibition of thymidine synthesis via thymidylate synthase selectively inhibits DNA synthesis over RNA synthesis. Due to their efficiency, these drugs are the most widely used cytostatics.
Thus, acetylation of histones is known to increase the expression of genes through transcription activation. Deacetylation performed by HDAC molecules has the opposite effect. By deacetylating the histone tails, the DNA becomes more tightly wrapped around the histone cores, making it harder for transcription factors to bind to the DNA.
Drug resistance can emerge as a result of continued and repetitive usage of a drug, giving pathogens time to develop defenses against drugs designed to kill them. [20] In cancer, overexpression, for instance in DNA methylation and histone deactylase, can cause deleterious effects which can enhance drug resistance behaviors such as drug efflux ...
Dialkylating agents can react with two different 7-N-guanine residues, and, if these are in different strands of DNA, the result is cross-linkage of the DNA strands, which prevents uncoiling of the DNA double helix. If the two guanine residues are in the same strand, the result is called limpet attachment of the drug molecule to the DNA.
Image illustrates DNA, RNA, and protein synthesis. The first two are nucleic acids. A nucleic acid inhibitor is a type of antibacterial that acts by inhibiting the production of nucleic acids. There are two major classes: DNA inhibitors and RNA inhibitors. [1] The antifungal flucytosine acts in a similar manner.
Azacitidine is the first drug to be approved by FDA for treating MDS and has been given orphan drug status. [2] [3] Procaine is a DNA-demethylating agent with growth-inhibitory effects in human cancer cells. [4] There are many other demethylating agents that can be used to inhibit the growth of other diseases. [5]