DNA, RNA, protein synthesis

Mechanism of Action A folate antagonist that inhibits the enzyme dihydrofolate reductase (DHFR). Therapeutic Effect Disrupts purine, DNA, RNA, protein synthesis,... 

Antipurine antimetabolite purine analog inhibits DNA, RNA, protein synthesis metabolized by xanthine oxidase... 

DNA/RNA/protein synthesis, not only for cancerous cells, but for all cells, hence the designator cytotoxic. 

Conventional chemotherapy drugs act as inhibitors for enzymes, notably for critical enzymes that pertain to DNA/RNA/protein synthesis. The idea is that by blocking one or another or all of these enzymes, cancer cell growth and proliferation will be stopped. Unfortunately, these drugs are nonselective, acting against normal cells as well, and are therefore categorized as cell toxic, or cytotoxic. 

Proteins involved in DNA, RNA, protein synthesis Gene regulation Cancer and control of cell proliferation... 

According to the cascade DNA- RNA- protein synthesis, disturbances of protein synthesis should be accompanied by alterations of RNA-metabolism. These are traceable by measuring "one way" urinary methylated RNA-catabolites. ... 

FIGURE 11.1 The fundamental process of information transfer in cells. Information encoded in the nucleotide sequence of DNA is transcribed through synthesis of an RNA molecule whose sequence is dictated by the DNA sequence. As the sequence of this RNA is read (as groups of three consecutive nucleotides) by the protein synthesis machinery, it is translated into the sequence of amino acids in a protein. This information tmiisfer system is encapsulated in the dogma DNA RNA protein. 

Before proceeding it is worth noting that the prokaryotes established the fundamental features of life in the coordinated production of DNA, RNA, proteins, saccharides and lipids, mainly from H, C, N, O, S and P and in the functional use of many inorganic elements including Na, K, Mg, Ca, Mn, Fe, Co, Ni, Cu, Zn, Mo, Cl and Se. In this book we deliberately stress this role of the available elements in the environment especially as they change with time in evolution in advance of that in cells. In evolution many of the functions of these molecules and ions remain only modified not fundamentally changed. While the uses of metal ions were restricted by equilibria (Sections 4.18 1.20), the synthesis of porphyrins allowed effectively novel elements,... 

Mechanism of Action An alkylating agent that inhibits DNAand RNA protein synthesis by cross-linking with DNA and RNA strands, preventing cell growth. Cell cycle-phase nonspedflc. Therapeutic Effect Potent immunosuppressant. Pharmacokinetics Well absorbed from the G1 tract. Protein binding low. Crosses the blood-brain barrier. Metabolized in the liver to active metabolites. Primarily excreted in urine. Removed by hemodialysis. Half-life 3-12 hr. 

Mechanism of Action An antibacterial UTI agent that inhibits the synthesis of bacterial DNA, RNA, proteins, and cell walls by altering or inactivating ribosomal proteins. Therapeutic Effect Bacteriostatic (bactericidal at high concentrations). Pharmacokinetics Microcrystalline form rapidly and completely absorbed macrocrystalline form more slowly absorbed. Food increases absorption. Protein binding 40%. Primarily concentrated in urine and kidneys. Metabolized in most body tissues. Primarily excreted in urine. Removed by hemodialysis. Half-life 20-60 min. 

FIGURE 1-2 Diverse living organisms share common chemical features. Birds, beasts, plants, and soil microorganisms share with humans the same basic structural units (cells) and the same kinds of macromolecules (DNA, RNA, proteins) made up of the same kinds of monomeric subunits (nucleotides, amino acids). They utilize the same pathways for synthesis of cellular components, share the same genetic code, and derive from the same evolutionary ancestors. Shown here is a detail from "The Garden of Eden," by Jan van Kessel the Younger (1626-1679). 

Homocysteine is formed as an intermediary amino acid in the methionine cycle (Fig. I). Methionine is metabolized to s-adenosylmethionine (SAM), the methyl donor in most methylation reactions and essential for the synthesis of creatinine, DNA, RNA, proteins, and phospholipids. SAM is converted by methyl donation to s-adenosylhomocysteine (SAH), which is then hydrolyzed to homocysteine. SAH is an inhibitor of methyl group donation from SAM. 

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