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Patellamide A
Patellamide A is a peptide natural product produced by ''Prochloron didemni'', a cyanobacterial symbiont of ''Lissoclinum patella'', and was first isolated in 1981. Patellamide A is one of many didemnid peptides. Other closely related peptides include Patellamide B, patellamides B, Patellamide C, C, and Patellamide D, D and trunkamide. The patellamides and trunkamide show moderate cytotoxicity and activity against multidrug resistant cancer cell lines. History Patellamide A was first isolated in 1981 from the tunicate ''L. patella'' collected from the reefs of Korror Island, Palau Islands. ''L. patella'' has been a rich source of peptide natural products. Aside from the patellamides, the lissoclinamides, ulicyclamide, ulithiacyclamide and ascidiacyclamide were all isolated from ''L. patella''. The absolute stereochemistry was later determined by X-ray crystallography. Biosynthesis Patellamide A originates from a ribosomal peptide, making it a member of the RiPPs, RiPP superfam ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Natural Product
A natural product is a natural compound or substance produced by a living organism—that is, found in nature. In the broadest sense, natural products include any substance produced by life. Natural products can also be prepared by chemical synthesis (both semisynthesis and total synthesis and have played a central role in the development of the field of organic chemistry by providing challenging synthetic targets). The term ''natural product'' has also been extended for commercial purposes to refer to cosmetics, dietary supplements, and foods produced from natural sources without added artificial ingredients. Within the field of organic chemistry, the definition of natural products is usually restricted to organic compounds isolated from natural sources that are produced by the pathways of primary or secondary metabolism. Within the field of medicinal chemistry, the definition is often further restricted to secondary metabolites. Secondary metabolites (or specialized meta ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Ribosomal
Ribosomes () are macromolecular machines, found within all cells, that perform biological protein synthesis (messenger RNA translation). Ribosomes link amino acids together in the order specified by the codons of messenger RNA molecules to form polypeptide chains. Ribosomes consist of two major components: the small and large ribosomal subunits. Each subunit consists of one or more ribosomal RNA molecules and many ribosomal proteins (). The ribosomes and associated molecules are also known as the ''translational apparatus''. Overview The sequence of DNA that encodes the sequence of the amino acids in a protein is transcribed into a messenger RNA (mRNA) chain. Ribosomes bind to the messenger RNA molecules and use the RNA's sequence of nucleotides to determine the sequence of amino acids needed to generate a protein. Amino acids are selected and carried to the ribosome by transfer RNA (tRNA) molecules, which enter the ribosome and bind to the messenger RNA chain via an anticodo ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Thiazoles
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 a ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Macrocycles
Macrocycles are often described as molecules and ions containing a Ring (chemistry), 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. So ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Epimerization
In stereochemistry, an epimer is one of a pair of diastereomers. The two epimers have opposite configuration at only one stereogenic center out of at least two. All other stereogenic centers in the molecules are the same in each. Epimerization is the interconversion of one epimer to the other epimer. Doxorubicin and epirubicin are two epimers that are used as drugs. Examples The stereoisomers β-D-glucopyranose and β-D- mannopyranose are epimers because they differ only in the stereochemistry at the C-2 position. The hydroxy group in β-D-glucopyranose is equatorial (in the "plane" of the ring), while in β-D-mannopyranose the C-2 hydroxy group is axial (up from the "plane" of the ring). These two molecules are epimers but, because they are not mirror images of each other, are not enantiomers. (Enantiomers have the same name, but differ in D and L classification.) They are also not sugar anomers, since it is not the anomeric carbon involved in the stereochemistry. Similarly, ... [...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] |
Thiazoline
Thiazolines (; or dihydrothiazoles) are a group of isomeric 5-membered heterocyclic compounds containing both sulfur and nitrogen in the ring. Although unsubstituted thiazolines are rarely encountered themselves, their derivative (chemistry), derivatives are more common and some are bioactive. For example, in a common post-translational modification, cysteine residues are converted into thiazolines. The name thiazoline originates from the Hantzsch–Widman nomenclature. Isomers Three structural isomers of thiazoline exist depending on the position of the double bond. These forms do not readily interconvert and hence are not tautomers. Of these 2-thiazoline is the most common. A fourth structure exists in which the N and S atoms are adjacent; this known as isothiazoline. Synthesis Thiazolines were first prepared by dialkylation of thioamides by Richard Willstatter in 1909. 2-Thiazolines are commonly prepared from 2-aminoethanethiols (e.g. cysteamine). They may also be synthe ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Oxazoline
Oxazoline is a five-membered heterocyclic organic compound with the formula . It is the parent of a family of compounds called oxazolines (emphasis on plural), which contain non-hydrogenic substituents on carbon and/or nitrogen. Oxazolines are the unsaturated analogues of oxazolidines, and they are isomeric with isoxazolines, where the N and O are directly bonded. Two isomers of oxazoline are known, depending on the location of the double bond. Oxazoline itself has no applications however oxazolines have been widely investigated for potential applications. These applications include use as ligands in asymmetric catalysis, as Protecting group#Carboxylic acid protecting groups, protecting groups for carboxylic acids and increasingly as monomers for the production of polymers. Isomers Synthesis The synthesis of 2-oxazoline rings is well established and in general proceeds via the cyclisation of a 2-amino alcohol (typically obtained by the reduction of an amino acid) with a suitabl ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Natural Products
A natural product is a natural compound or substance produced by a living organism—that is, found in nature. In the broadest sense, natural products include any substance produced by life. Natural products can also be prepared by chemical synthesis (both semisynthesis and total synthesis and have played a central role in the development of the field of organic chemistry by providing challenging synthetic targets). The term ''natural product'' has also been extended for commercial purposes to refer to cosmetics, dietary supplements, and foods produced from natural sources without added artificial ingredients. Within the field of organic chemistry, the definition of natural products is usually restricted to organic compounds isolated from natural sources that are produced by the pathways of primary or secondary metabolism. Within the field of medicinal chemistry, the definition is often further restricted to secondary metabolites. Secondary metabolites (or specialized metab ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
RiPPs
Ribosomally synthesized and post-translationally modified peptides (RiPPs), also known as ribosomal natural products, are a diverse class of natural products of ribosomal origin. Consisting of more than 20 sub-classes, RiPPs are produced by a variety of organisms, including prokaryotes, eukaryotes, and archaea, and they possess a wide range of biological functions. As a consequence of the falling cost of genome sequencing and the accompanying rise in available genomic data, scientific interest in RiPPs has increased in the last few decades. Because the chemical structures of RiPPs are more closely predictable from genomic data than are other natural products (e.g. alkaloids, terpenoids), their presence in sequenced organisms can, in theory, be identified rapidly. This makes RiPPs an attractive target of modern natural product discovery efforts. Definition RiPPs consist of any peptides (i.e. molecular weight below 10 kDa) that are ribosomally-produced and undergo some degree of e ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
X-ray Crystallography
X-ray crystallography is the experimental science of determining the atomic and molecular structure of a crystal, in which the crystalline structure causes a beam of incident X-rays to Diffraction, diffract in specific directions. By measuring the angles and intensities of the X-ray diffraction, a crystallography, crystallographer can produce a three-dimensional picture of the density of electrons within the crystal and the positions of the atoms, as well as their chemical bonds, crystallographic disorder, and other information. X-ray crystallography has been fundamental in the development of many scientific fields. In its first decades of use, this method determined the size of atoms, the lengths and types of chemical bonds, and the atomic-scale differences between various materials, especially minerals and alloys. The method has also revealed the structure and function of many biological molecules, including vitamins, drugs, proteins and nucleic acids such as DNA. X-ray crystall ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
