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Cyclotide
In biochemistry, cyclotides are small, disulfide-rich peptides isolated from plants. Typically containing 28-37 amino acids, they are characterized by their head-to-tail cyclised peptide backbone and the interlocking arrangement of their three disulfide bonds. These combined features have been termed the cyclic cystine knot (CCK) motif. To date, over 100 cyclotides have been isolated and characterized from species of the families Rubiaceae, Violaceae, and Cucurbitaceae. Cyclotides have also been identified in agriculturally important families such as the Fabaceae and Poaceae. Structure Cyclotides have a well-defined three-dimensional structure due to their interlocking disulfide bonds and cyclic peptide backbone. Backbone loops and selected residues are labeled on the structure to help orientation. The amino acid sequence (single-letter amino acid representation) for this peptide is indicated on the sequence diagram to the right. One of the interesting features of cyclic p ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Cystine Knot
A cystine knot is a protein structural motif containing three disulfide bridges (formed from pairs of cysteine residues). The sections of polypeptide that occur between two of them form a loop through which a third disulfide bond passes, forming a rotaxane substructure. The cystine knot motif stabilizes protein structure and is conserved in proteins across various species. There are three types of cystine knot, which differ in the topology of the disulfide bonds: * The growth factor cystine knot (GFCK) * inhibitor cystine knot (ICK) common in spider and snail toxins * Cyclic Cystine Knot, or cyclotide The growth factor cystine knot was first observed in the structure of nerve growth factor (NGF), solved by X-ray crystallography and published in 1991 by Tom Blundell in Nature.; The GFCK is present in four superfamilies. These include nerve growth factor, transforming growth factor beta (TGF-β), platelet-derived growth factor, and glycoprotein hormones including human chorioni ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Biochemistry
Biochemistry or biological chemistry is the study of chemical processes within and relating to living organisms. A sub-discipline of both chemistry and biology, biochemistry may be divided into three fields: structural biology, enzymology and metabolism. Over the last decades of the 20th century, biochemistry has become successful at explaining living processes through these three disciplines. Almost all areas of the life sciences are being uncovered and developed through biochemical methodology and research. Voet (2005), p. 3. Biochemistry focuses on understanding the chemical basis which allows biological molecules to give rise to the processes that occur within living cells and between cells,Karp (2009), p. 2. in turn relating greatly to the understanding of tissues and organs, as well as organism structure and function.Miller (2012). p. 62. Biochemistry is closely related to molecular biology, which is the study of the molecular mechanisms of biological phenomena.As ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Helicoverpa Size
''Helicoverpa'' is a genus of moths in the family Noctuidae first described by David F. Hardwick in 1965. Some species are among the worst Lepidopteran agricultural pests in the world, and three species (''H. armigera'', ''H. zea'', and ''H. punctigera'') migrate long distances both with and without human transportation, mixing resistance alleles along the way. Extant species * '' Helicoverpa armigera'' (Hübner, 1805) - cotton bollworm * ''Helicoverpa assulta'' (Guenée, 1852) * '' Helicoverpa atacamae'' Hardwick, 1965 * '' Helicoverpa fletcheri'' Hardwick, 1965 * '' Helicoverpa gelotopoeon'' (Dyar, 1921) * '' Helicoverpa hardwicki'' Matthews, 1999 * '' Helicoverpa hawaiiensis'' Quaintance & Brues, 1905 * '' Helicoverpa helenae'' Hardwick, 1965 * '' Helicoverpa pallida'' Hardwick, 1965 * '' Helicoverpa prepodes'' Common, 1985 * ''Helicoverpa punctigera'' Wallengren, 1860 * '' Helicoverpa titicacae'' * '' Helicoverpa toddi'' Hardwick, 1965 * ''Helicoverpa zea ''Helicoverpa ze ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Möbius Strip
In mathematics, a Möbius strip, Möbius band, or Möbius loop is a surface that can be formed by attaching the ends of a strip of paper together with a half-twist. As a mathematical object, it was discovered by Johann Benedict Listing and August Ferdinand Möbius in 1858, but it had already appeared in Roman mosaics from the third century CE. The Möbius strip is a non-orientable surface, meaning that within it one cannot consistently distinguish clockwise from counterclockwise turns. Every non-orientable surface contains a Möbius strip. As an abstract topological space, the Möbius strip can be embedded into three-dimensional Euclidean space in many different ways: a clockwise half-twist is different from a counterclockwise half-twist, and it can also be embedded with odd numbers of twists greater than one, or with a knotted centerline. Any two embeddings with the same knot for the centerline and the same number and direction of twists are topologically equivalent. All of t ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Cis-proline
Proline (symbol Pro or P) is an organic acid classed as a proteinogenic amino acid (used in the biosynthesis of proteins), although it does not contain the amino group but is rather a secondary amine. The secondary amine nitrogen is in the protonated form (NH2+) under biological conditions, while the carboxyl group is in the deprotonated −COO− form. The "side chain" from the α carbon connects to the nitrogen forming a pyrrolidine loop, classifying it as a aliphatic amino acid. It is non-essential in humans, meaning the body can synthesize it from the non-essential amino acid L-glutamate. It is encoded by all the codons starting with CC (CCU, CCC, CCA, and CCG). Proline is the only proteinogenic secondary amino acid which is a secondary amine, as the nitrogen atom is attached both to the α-carbon and to a chain of three carbons that together form a five-membered ring. History and etymology Proline was first isolated in 1900 by Richard Willstätter who obtained the amino a ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Homology (biology)
In biology, homology is similarity due to shared ancestry between a pair of structures or genes in different taxa. A common example of homologous structures is the forelimbs of vertebrates, where the wings of bats and birds, the arms of primates, the front flippers of whales and the forelegs of four-legged vertebrates like dogs and crocodiles are all derived from the same ancestral tetrapod structure. Evolutionary biology explains homologous structures adapted to different purposes as the result of descent with modification from a common ancestor. The term was first applied to biology in a non-evolutionary context by the anatomist Richard Owen in 1843. Homology was later explained by Charles Darwin's theory of evolution in 1859, but had been observed before this, from Aristotle onwards, and it was explicitly analysed by Pierre Belon in 1555. In developmental biology, organs that developed in the embryo in the same manner and from similar origins, such as from matching p ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Biological Activity
In pharmacology, biological activity or pharmacological activity describes the beneficial or adverse effects of a drug on living matter. When a drug is a complex chemical mixture, this activity is exerted by the substance's active ingredient or pharmacophore but can be modified by the other constituents. Among the various properties of chemical compounds, pharmacological/biological activity plays a crucial role since it suggests uses of the compounds in the medical applications. However, chemical compounds may show some adverse and toxic effects which may prevent their use in medical practice. Activity is generally dosage-dependent. Further, it is common to have effects ranging from beneficial to adverse for one substance when going from low to high doses. Activity depends critically on fulfillment of the ADME criteria. To be an effective drug, a compound not only must be active against a target, but also possess the appropriate ADME (Absorption, Distribution, Metabolism, and ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Physical Chemistry
Physical chemistry is the study of macroscopic and microscopic phenomena in chemical systems in terms of the principles, practices, and concepts of physics such as motion, energy, force, time, thermodynamics, quantum chemistry, statistical mechanics, analytical dynamics and chemical equilibria. Physical chemistry, in contrast to chemical physics, is predominantly (but not always) a supra-molecular science, as the majority of the principles on which it was founded relate to the bulk rather than the molecular or atomic structure alone (for example, chemical equilibrium and colloids). Some of the relationships that physical chemistry strives to resolve include the effects of: # Intermolecular forces that act upon the physical properties of materials ( plasticity, tensile strength, surface tension in liquids). # Reaction kinetics on the rate of a reaction. # The identity of ions and the electrical conductivity of materials. # Surface science and electrochemistry of cell membrane ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Uterine Contraction
Uterine contractions are muscle contractions of the uterine smooth muscle that occur during the menstrual cycle and labour. Uterine contractions occur throughout the menstrual cycle in the non-pregnant state and throughout gestation. Throughout menstrual cycle Uterine contractions that occur throughout the menstrual cycle, also termed ''endometrial waves'' or ''contractile waves'', appear to involve only the sub-endometrial layer of the myometrium. Follicular and luteal phase In the early follicular phase, uterine contractions in the non-pregnant woman occur 1—2 times per minute and last 10–15 seconds with a low intensity of usually 30 mmHg or less. This sub-endometrial layer is rich in estrogen and progesterone receptors. The frequency of contractions increases to 3–4 per minute towards ovulation. During the luteal phase, the frequency and intensity decrease, possibly to facilitate any implantation. Menstruation If implantation does not occur, the frequency of contraction ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Uterotonic
A uterotonic, also known as ecbolic, are pharmacological agents used to induce contraction or greater tonicity of the uterus. Uterotonics are used both to induce labor and to reduce postpartum hemorrhage. Labor induction in the third trimester of pregnancy may be required due to medical necessity, or may be desired for social reasons. Generally, labor induction is indicated when the risk of carrying the pregnancy outweighs the risk of delivering. These reason include, but are not limited to, pregnancies that are prolonged, prelabor rupture of the fetal membranes, and concerns about the health and safety of the mother and/or child. There are multiple techniques available to stimulate uterine contractions including mechanical, pharmacological, and alternative medicine methods to initiate contractions prior to spontaneous onset of labor. Postpartum hemorrhage, also known as PPH, is defined as a loss of 500 mL or greater of blood within 24 hours after giving birth. It is one of the lea ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Trypsin
Trypsin is an enzyme in the first section of the small intestine that starts the digestion of protein molecules by cutting these long chains of amino acids into smaller pieces. It is a serine protease from the PA clan superfamily, found in the digestive system of many vertebrates, where it hydrolyzes proteins. Trypsin is formed in the small intestine when its proenzyme form, the trypsinogen produced by the pancreas, is activated. Trypsin cuts peptide chains mainly at the carboxyl side of the amino acids lysine or arginine. It is used for numerous biotechnological processes. The process is commonly referred to as trypsin proteolysis or trypsinization, and proteins that have been digested/treated with trypsin are said to have been trypsinized. Trypsin was discovered in 1876 by Wilhelm Kühne and was named from the Ancient Greek word for rubbing since it was first isolated by rubbing the pancreas with glycerin. Function In the duodenum, trypsin catalyzes the hydrolysis of pept ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Neurotensin
Neurotensin is a 13 amino acid neuropeptide that is implicated in the regulation of luteinizing hormone and prolactin release and has significant interaction with the dopaminergic system. Neurotensin was first isolated from extracts of bovine hypothalamus based on its ability to cause a visible vasodilation in the exposed cutaneous regions of anesthetized rats. Neurotensin is distributed throughout the central nervous system, with highest levels in the hypothalamus, amygdala and nucleus accumbens. It induces a variety of effects, including analgesia, hypothermia and increased locomotor activity. It is also involved in regulation of dopamine pathways. In the periphery, neurotensin is found in enteroendocrine cells of the small intestine, where it leads to secretion and smooth muscle contraction. Sequence and biosynthesis Neurotensin shares significant sequence similarity in its 6 C-terminal amino acids with several other neuropeptides, including neuromedin N (which is derived ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
