Bacteria protein synthesis inhibitors

Although most of the compounds produced hy Alternaria are generally nontoxic, altemariol monomethyl ether has been shown to be mutagenic in bacteria (Ames tests) [166]. Tenuazonic acid (TA) is a protein synthesis inhibitor and is capable of chelating metal ions and forming nitrosamines. TA is also produced... 

Metronidazole and clindamycin are protein synthesis inhibitors that inhibit bacteria by interacting with the DNA to cause a loss of helical DNA structure and strand break-... 

The mitochondrial ribosomes of mammals are small (about 555) and insensitive to erythromycin and lincomycin, although these antibiotics penetrate freely into the mitochondria. These ribosomes are sensitive to chloramphenicol which, fortunately, does not normally penetrate into mammalian mitochondria. Chloroplasts have ribosomes that are sensitive to most of the protein synthesis inhibitors that injure bacteria (Kiintzel and Noll, 1967). 

C25H35N5O7 517.581 Nucleoside antibiotic. Prod, by Strepto-myces plicatus. Potent inhibitor of in vitro protein synthesis. Inhibitor of gram-positive and gram-negative bacteria. Needies eOH aq.). 

Chlamydomonas reinhardi is sensitive to the protein synthesis inhibitor, erythromycin. At the time, some erythromycin-resistant strains had been isolated and described, and we were considering experimental approaches to locate the sites of structural genes for proteins of plastid ribosomes. It seemed reasonable to use erythromycin resistance as a genetic marker if we could be certain that the antibiotic interacts with some part of the chloroplast ribosome and was not lethal for some other reason. Erythromycin was known to bind to the large subunit of Escherichia coli ribosomes, and the alteration leading to resistance in the bacteria was found to reside in a single protein in the 50 S subunit. ... 

Feedback inhibition of amino acid transporters by amino acids synthesized by the cells might be responsible for the well known fact that blocking protein synthesis by cycloheximide in Saccharomyces cerevisiae inhibits the uptake of most amino acids [56]. Indeed, under these conditions, endogenous amino acids continue to accumulate. This situation, which precludes studying amino acid transport in yeast in the presence of inhibitors of protein synthesis, is very different from that observed in bacteria, where amino acid uptake is commonly measured in the presence of chloramphenicol in order to isolate the uptake process from further metabolism of accumulated substances. In yeast, when nitrogen starvation rather than cycloheximide is used to block protein synthesis, this leads to very high uptake activity. This fact supports the feedback inhibition interpretation of the observed cycloheximide effect. 

Mupirocin is not related to any of the sys-temically used antibiotics. It is an inhibitor of bacterial protein synthesis and is especially active against gram-positive aerobic bacteria, e.g. methicillin-resistant S. aureus and group A beta-hemolytic streptococci. Absorption through the skin is minimal. Intranasal application may be associated with irritation of mucous membranes. 

Erythromycin Prevents bacterial protein synthesis by binding to the 50S ribosomal subunit Bacteriostatic activity against susceptible bacteria Community-acquired pneumonia t pertussis corynebacterial, and chlamydial infections Oral, IV hepatic clearance (half-life 1.5 h) dosed every 6 h cytochrome P450 inhibitor Toxicity Gastrointestinal upset, hepatotoxicity, QTC prolongation... 

Inhibitors are substances that tend to decrease the rate of an enzyme-catalysed reaction. Although some act on the substrate, the discussion here will be restricted to those inhibitors which combine directly with the enzyme. Inhibitors have many uses, not only in the determination of the characteristics of enzymes, but also in aiding research into metabolic pathways where an inhibited enzyme will allow metabolites to build up so that they are present in detectable levels. Another important use is in the control of infection where drugs such as sulphanilamides competitively inhibit the synthesis of tetrahydrofolates which are vitamins essential to the growth of some bacteria. Many antibiotics are inhibitors of bacterial protein synthesis (e.g. tetracyclin) and cell-wall synthesis (e.g. penicillin). 

T There are several distinct types of inhibitors of nucleotide biosynthesis, each type acting at different points in the pathways to purine or pyrimidine nucleotides. All these inhibitors are very toxic to cells, especially rapidly growing cells, such as those of tumors or bacteria, because interruption of the supply of nucleotides seriously limits the cell s capacity to synthesize the nucleic acids necessary for protein synthesis and cell replication. In some cases, the toxic effect of such inhibitors makes them useful in cancer chemotherapy or in the treatment of bacterial infections. However, some of these agents can also damage the rapidly replicating cells of the intestinal tract and bone marrow. This danger imposes limits on the doses that can be used safely. 

Chloramphenicol and chlortetracycline were the first antibiotics recognized to be inhibitors of protein synthesis on the basis of findings that they inhibited induced enzyme syntheses in bacteria after induction had occurred and syntheses had been under way for considerable periods of time37. ... 

Molds also produce complex products of secondary metabolism. These secondary metabolites include chemicals used to ensure that the molds maintain their niche within their current habitat. These chemicals may suppress the growth of bacteria or other molds (antibiotic effect), or may be toxic to other eukaryotic cells (mycotoxic effect),. Mycotoxins may function as inhibitors of DNA, RNA, and protein synthesis. The production of secondary metabolites... 

The answer is c. (Murray, pp 452—467. Scriver, pp 3—45. Sack, pp 1—40. Wilson, pp 101-120.) Prokaryotic ribosomes have a sedimentation coefficient of 70S and are composed of SOS and 30S subunits. Eukaryotic cytoplasmic ribosomes, either free or bound to the endoplasmic reticulum, are larger—60S and 40S subunits that associate to an SOS ribosome. Nuclear ribosomes are attached to the endoplasmic reticulum of the nuclear membrane. Ribosomes in chloroplasts and mitochondria of eukaryotic cells are more similar to prokaryotic ribosomes than to eukaryotic cytosolic ribosomes. Like bacterial ribosomes, chloroplast and mitochondrial ribosomes use a formylated tRNA. In addition, they are sensitive to many of the inhibitors of protein synthesis in bacteria. 

Bacterial infections are treated with antibiotics. There are many antibiotics available, but they fall into three major groups based on their mode of action inhibitors of bacterial nucleic acid synthesis inhibitors of cell wall synthesis and inhibition of bacterial protein synthesis. Resistance of bacteria to commonly-used antibiotics has become a major problem necessitating the development of new antibiotics. Tuberculosis infection is difficult to treat and requires a combination of at least three different antibiotics. 

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