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Thiopeptides
Thiopeptides (thiazolyl peptides) are a class of peptide antibiotics produced by bacteria. They have antibiotic activity against Gram-positive bacteria, but little or no activity against Gram-negative bacteria. Many of the members of this class show activity against methicillin-resistant ''Staphylococcus aureus'' (MRSA) and are therefore subjects of research interest. There are over 100 members of this class known. __TOC__ Chemical structure Thiopeptides are sulfur-rich macrocyclic peptides containing highly-modified amino acids. They are characterized by a nitrogen-containing six-membered ring (such as piperidine, dehydropiperidine, or pyridine) substituted with multiple thiazole rings and dehydroamino acids. A macrocylic ring serves as a scaffold for a tail that also incorporates modified amino acids often with azole Azoles are a class of five-membered heterocyclic compounds containing a nitrogen atom and at least one other non-carbon atom (i.e. nitrogen, sulfur, or oxygen ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Lactocillin
Lactocillin is a thiopeptide antibiotic which is encoded for and produced by biosynthetic genes clusters in the bacteria ''Lactobacillus gasseri''. Lactocillin was discovered and purified in 2014. ''Lactobacillus gasseri'' is one of the four ''Lactobacillus'' bacteria found to be most common in the human vaginal microbiome. Due to increasing levels of pathogenic resistance to known antibiotics, novel antibiotics are increasingly valuable. Lactocillin could function as a new antibiotic that could help people fight off infections that are resistant to many other antibiotics. Biosynthetic Gene Clusters Lactocillin is produced by a biosynthetic gene cluster, which is a group of genes in bacteria that work together to make a secondary metabolite. Secondary metabolites are molecules with many different chemical structures and functions, and in this case, lactocillin functions as an antibiotic. Biosynthetic gene clusters are similar to operons in bacteria in that they both code for ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Nosiheptide
Nosiheptide is a thiopeptide antibiotic produced by the bacterium ''Streptomyces actuosus''. Chemical classification Nosiheptide is classified, along with several others, as an e series thiopeptide characterized by a nitrogen containing, 6-membered Heterocyclic compound, heterocycle in a 2,3,5,6 substituted fashion central to multiple azoles (or azolines) and Amino acid, dehydroamino acids along with a macrocyclic core. Nosiheptide is constructed solely of proteinogenic amino acids and has Ribosome, ribosomal origin, making it a member of the ribosomally synthesized and post-translationally modified peptides, ribosomally synthesized and posttranslationally modified peptide family of natural products. Thiopeptides such as nosiheptide have potent activity against various bacterial pathogens, primarily Gram-positive bacteria, gram positive, including methicillin-resistant Staphylococcus aureus, penicillin-resistant Streptococcus pneumoniae, and Vancomycin Resistant Enterococci, vanc ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Thiostrepton
Thiostrepton is a natural cyclic oligopeptide antibiotic of the thiopeptide class, derived from several strains of streptomycetes, such as '' Streptomyces azureus'' and '' Streptomyces laurentii''. Thiostrepton is a natural product of the ribosomally synthesized and post-translationally modified peptide (RiPP) class. History Thiostrepton was discovered by Donovick ''et al.'' who described its antibacterial properties in 1955. Dorothy Crowfoot Hodgkin solved the structure of thiostrepton in 1970. Early in 1978, Bycroft and Gowland proposed the biosynthesis of thiostrepton, which was still unclear until 2009. Several studies of thiopeptide biosynthesis have been contemporarily published in 2009 and two of them (Liao ''et al.'' and Kelly ''et al.'') included the similar biosynthesis of thiostrepton: it's ribosomally synthesized from thiostrepton biosynthetic genes (tsr genes) and posttranslational modification is needed. A total synthesis of thiostrepton was completed by K.C ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Cyclothiazomycin
The cyclothiazomycins are a group of natural products, classified as thiopeptides, which are produced by various ''Streptomyces'' species of bacteria. These compounds are ribosomally synthesized and post-translationally modified peptides (RiPPs) and can be further classified as thiopeptides. The overall structure of the cyclothiazomycins comprises a macrocyclic bicyclic peptide containing several thiazoles and thiazolines. The cyclothiazomycins are reported to have multiple inhibitory effects ranging from decreasing blood pressure to interfering with RNA transcription; they also exhibit some antibiotic activity. History Cylothiazomycin A was first isolated from ''Streptomyces'' sp. NR0516 in 1991. The structure of cyclothiazomycin A was solved via NMR spectroscopy and chemical degradation. Previously, a peptide compound 5102-II had been isolated in 1982 from ''Streptomyces hygroscopicus'' 10-22. The discovery of the genes responsible for the biosynthesis of cyclothiazomyc ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Peptide
Peptides are short chains of amino acids linked by peptide bonds. A polypeptide is a longer, continuous, unbranched peptide chain. Polypeptides that have a molecular mass of 10,000 Da or more are called proteins. Chains of fewer than twenty amino acids are called oligopeptides, and include dipeptides, tripeptides, and tetrapeptides. Peptides fall under the broad chemical classes of biological polymers and oligomers, alongside nucleic acids, oligosaccharides, polysaccharides, and others. Proteins consist of one or more polypeptides arranged in a biologically functional way, often bound to ligands such as coenzymes and cofactors, to another protein or other macromolecule such as DNA or RNA, or to complex macromolecular assemblies. Amino acids that have been incorporated into peptides are termed residues. A water molecule is released during formation of each amide bond.. All peptides except cyclic peptides have an N-terminal (amine group) and C-terminal (carboxyl g ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Antibiotics
An antibiotic is a type of antimicrobial substance active against bacteria. It is the most important type of antibacterial agent for fighting pathogenic bacteria, bacterial infections, and antibiotic medications are widely used in the therapy, treatment and antibiotic prophylaxis, prevention of such infections. They may either bactericide, kill or bacteriostatic agent, inhibit the growth of bacteria. A limited number of antibiotics also possess antiprotozoal activity. Antibiotics are not effective against viruses such as the ones which cause the common cold or influenza. Drugs which inhibit growth of viruses are termed antiviral drugs or antivirals. Antibiotics are also not effective against fungi. Drugs which inhibit growth of fungi are called antifungal drugs. Sometimes, the term ''antibiotic''—literally "opposing life", from the Greek language, Greek roots ἀντι ''anti'', "against" and βίος ''bios'', "life"—is broadly used to refer to any substance used against ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Gram-positive Bacteria
In bacteriology, gram-positive bacteria are bacteria that give a positive result in the Gram stain test, which is traditionally used to quickly classify bacteria into two broad categories according to their type of cell wall. The Gram stain is used by microbiologists to place bacteria into two main categories, gram-positive (+) and gram-negative (−). Gram-positive bacteria have a thick layer of peptidoglycan within the cell wall, and gram-negative bacteria have a thin layer of peptidoglycan. Gram-positive bacteria retain the crystal violet stain used in the test, resulting in a purple color when observed through an optical microscope. The thick layer of peptidoglycan in the bacterial cell wall retains the stain after it has been fixed in place by iodine. During the decolorization step, the decolorizer removes crystal violet from all other cells. Conversely, gram-negative bacteria cannot retain the violet stain after the decolorization step; alcohol used in this stage ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Gram-negative Bacteria
Gram-negative bacteria are bacteria that, unlike gram-positive bacteria, do not retain the Crystal violet, crystal violet stain used in the Gram staining method of bacterial differentiation. Their defining characteristic is that their cell envelope consists of a thin peptidoglycan gram-negative cell wall, cell wall sandwiched between an inner (Cytoplasm, cytoplasmic) Cell membrane, membrane and an Bacterial outer membrane, outer membrane. These bacteria are found in all environments that support life on Earth. Within this category, notable species include the model organism ''Escherichia coli'', along with various pathogenic bacteria, such as ''Pseudomonas aeruginosa'', ''Chlamydia trachomatis'', and ''Yersinia pestis''. They pose significant challenges in the medical field due to their outer membrane, which acts as a protective barrier against numerous Antibiotic, antibiotics (including penicillin), Detergent, detergents that would normally damage the inner cell membrane, and the ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Methicillin-resistant Staphylococcus Aureus
Methicillin-resistant ''Staphylococcus aureus'' (MRSA) is a group of gram-positive bacteria that are genetically distinct from other strains of ''Staphylococcus aureus''. MRSA is responsible for several difficult-to-treat infections in humans. It caused more than 100,000 deaths worldwide attributable to antimicrobial resistance in 2019. MRSA is any strain of ''S. aureus'' that has developed (through mutation) or acquired (through horizontal gene transfer) a multiple drug resistance to beta-lactam antibiotics. Beta-lactam (β-lactam) antibiotics are a broad-spectrum group that include some penams (penicillin derivatives such as methicillin and oxacillin) and cephems such as the cephalosporins. Strains unable to resist these antibiotics are classified as methicillin-susceptible ''S. aureus'', or MSSA. MRSA infection is common in hospitals, prisons, and nursing homes, where people with open wounds, invasive devices such as catheters, and weakened immune systems are at greate ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Macrocyclic
Macrocycles are often described as molecules and ions containing a ring of twelve or more atoms. Classical examples include the crown ethers, calixarenes, porphyrins, and cyclodextrins. Macrocycles describe a large, mature area of chemistry. Synthesis The formation of macrocycles by ring-closure is called macrocyclization. The central challenge to macrocyclization is that ring-closing reactions do not favor the formation of large rings. Instead, medium sized rings or polymers tend to form. Early macrocyclizations were achieved ketonic decarboxylations for the preparation of terpenoid macrocycles. So, while Ružička was able to produce various macrocycles, the yields were low. This kinetic problem can be addressed by using high-dilution reactions, whereby intramolecular processes are favored relative to polymerizations. Reactions amenable to high dilution include Dieckmann condensation and related based-induced reactions of esters with remote halides. Some macrocyclizat ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Thiazole
Thiazole (), or 1,3-thiazole, is a 5-membered heterocyclic compound that contains both sulfur and nitrogen. The term 'thiazole' also refers to a large family of derivatives. Thiazole itself is a pale yellow liquid with a pyridine-like odor and the molecular formula C3H3NS. The thiazole ring is notable as a component of the vitamin thiamine (B1). Molecular and electronic structure Thiazoles are members of the azoles, heterocycles that include imidazoles and oxazoles. Thiazole can also be considered a functional group when part of a larger molecule. Being planar thiazoles are characterized by significant pi-electron delocalization and have some degree of aromaticity, more so than the corresponding oxazoles. This aromaticity is evidenced by the 1H NMR chemical shift of the ring protons, which absorb between 7.27 and 8.77 ppm, indicating a strong diamagnetic ring current. The calculated pi-electron density marks C5 as the primary site for electrophilic substitution, and C2-H ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
