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β-hairpin
The beta hairpin (sometimes also called beta-ribbon or beta-beta unit) is a simple protein structural motif involving two beta strands that look like a hairpin. The motif consists of two strands that are adjacent in primary structure, oriented in an antiparallel direction (the N-terminus of one sheet is adjacent to the C-terminus of the next), and linked by a short loop of two to five amino acids. Beta hairpins can occur in isolation or as part of a series of hydrogen bonded strands that collectively comprise a beta sheet. Researchers such as Francisco Blanco ''et al.'' have used protein NMR to show that beta-hairpins can be formed from isolated short peptides in aqueous solution, suggesting that hairpins could form nucleation sites for protein folding. Classification Beta hairpins were originally categorized solely by the number of amino acid residues in their loop sequences, such that they were named one-residue, two-residue, etc. This system, however, is somewhat ambiguous ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Beta Hairpin
The beta hairpin (sometimes also called beta-ribbon or beta-beta unit) is a simple protein structural motif involving two beta strands that look like a Hairpin (fashion), hairpin. The motif consists of two strands that are adjacent in primary structure, oriented in an Antiparallel (biochemistry), antiparallel direction (the N-terminus of one sheet is adjacent to the C-terminus of the next), and linked by a short loop of two to five amino acids. Beta hairpins can occur in isolation or as part of a series of hydrogen bonded strands that collectively comprise a beta sheet. Researchers such as Francisco J. Blanco, Francisco Blanco ''et al.'' have used protein NMR to show that beta-hairpins can be formed from isolated short peptides in aqueous solution, suggesting that hairpins could form nucleation sites for protein folding. Classification Beta hairpins were originally categorized solely by the number of amino acid residues in their loop sequences, such that they were named one-resid ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Beta Strand
The beta sheet (β-sheet, also β-pleated sheet) is a common structural motif, motif of the regular protein secondary structure. Beta sheets consist of beta strands (β-strands) connected laterally by at least two or three backbone chain, backbone hydrogen bonds, forming a generally twisted, pleated sheet. A β-strand is a stretch of peptide, polypeptide chain typically 3 to 10 amino acids long with backbone in an extended conformational isomerism, conformation. The supramolecular association of β-sheets has been implicated in the formation of the Amyloid fibril, fibrils and Amyloid plaques, protein aggregates observed in amyloidosis, Alzheimer's disease and other Proteinopathy, proteinopathies. History The first β-sheet structure was proposed by William Astbury in the 1930s. He proposed the idea of hydrogen bonding between the peptide bonds of parallel or antiparallel extended β-strands. However, Astbury did not have the necessary data on the bond geometry of the amino acids ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Beta Sheet
The beta sheet (β-sheet, also β-pleated sheet) is a common motif of the regular protein secondary structure. Beta sheets consist of beta strands (β-strands) connected laterally by at least two or three backbone hydrogen bonds, forming a generally twisted, pleated sheet. A β-strand is a stretch of polypeptide chain typically 3 to 10 amino acids long with backbone in an extended conformation. The supramolecular association of β-sheets has been implicated in the formation of the fibrils and protein aggregates observed in amyloidosis, Alzheimer's disease and other proteinopathies. History The first β-sheet structure was proposed by William Astbury in the 1930s. He proposed the idea of hydrogen bonding between the peptide bonds of parallel or antiparallel extended β-strands. However, Astbury did not have the necessary data on the bond geometry of the amino acids in order to build accurate models, especially since he did not then know that the peptide bond was planar. ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Beta Bulge
A beta bulge can be described as a localized disruption of the regular hydrogen bonding of beta sheet by inserting extra residues into one or both hydrogen bonded β-strands. Types β-bulges can be grouped according to their length of the disruption, the number of residues inserted into each strand, whether the disrupted β-strands are parallel or antiparallel and by their dihedral angles (which controls the placement of their side chains). Two types occur commonly. One, the ''classic beta bulge'', occurs within, or at the edge of, antiparallel beta-sheet; the first residue at the outwards bulge typically has the αR, rather than the normal β, conformation. The other type is the G1 ''beta bulge'', of which there are two common sorts, both mainly occurring in association with antiparallel sheet; one residue has the αL conformation and is usually a glycine. In one sort, the beta bulge loop, one of the hydrogen bonds of the beta-bulge also forms a beta turn or alpha turn, such that ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Indole
Indole is an organic compound with the formula . Indole is classified as an aromatic heterocycle. It has a bicyclic structure, consisting of a six-membered benzene ring fused to a five-membered pyrrole ring. Indoles are derivatives of indole where one or more of the hydrogen atoms have been replaced by substituent groups. Indoles are widely distributed in nature, most notably as amino acid tryptophan and neurotransmitter serotonin. General properties and occurrence Indole is a solid at room temperature. It occurs naturally in human feces and has an intense fecal odor. At very low concentrations, however, it has a flowery smell, and is a constituent of many perfumes. It also occurs in coal tar. It has been identified in cannabis. It is the main volatile compound in stinky tofu. When indole is a substituent on a larger molecule, it is called an ''indolyl group'' by systematic nomenclature. Indole undergoes electrophilic substitution, mainly at position 3 (see diagram in ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Water-soluble
In chemistry, solubility is the ability of a substance, the solute, to form a solution with another substance, the solvent. Insolubility is the opposite property, the inability of the solute to form such a solution. The extent of the solubility of a substance in a specific solvent is generally measured as the concentration of the solute in a saturated solution, one in which no more solute can be dissolved. At this point, the two substances are said to be at the solubility equilibrium. For some solutes and solvents, there may be no such limit, in which case the two substances are said to be " miscible in all proportions" (or just "miscible"). The solute can be a solid, a liquid, or a gas, while the solvent is usually solid or liquid. Both may be pure substances, or may themselves be solutions. Gases are always miscible in all proportions, except in very extreme situations,J. de Swaan Arons and G. A. M. Diepen (1966): "Gas—Gas Equilibria". ''Journal of Chemical Physics' ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
α-helices
An alpha helix (or α-helix) is a sequence of amino acids in a protein that are twisted into a coil (a helix). The alpha helix is the most common structural arrangement in the secondary structure of proteins. It is also the most extreme type of local structure, and it is the local structure that is most easily predicted from a sequence of amino acids. The alpha helix has a right-handed helix conformation in which every backbone N−H group hydrogen bonds to the backbone C=O group of the amino acid that is four residues earlier in the protein sequence. Other names The alpha helix is also commonly called a: * Pauling–Corey–Branson α-helix (from the names of three scientists who described its structure) * 3.613-helix because there are 3.6 amino acids in one ring, with 13 atoms being involved in the ring formed by the hydrogen bond (starting with amidic hydrogen and ending with carbonyl oxygen) Discovery In the early 1930s, William Astbury showed that there were dras ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Van Der Waals Forces
In molecular physics and chemistry, the van der Waals force (sometimes van der Waals' force) is a distance-dependent interaction between atoms or molecules. Unlike ionic or covalent bonds, these attractions do not result from a chemical electronic bond; they are comparatively weak and therefore more susceptible to disturbance. The van der Waals force quickly vanishes at longer distances between interacting molecules. Named after Dutch physicist Johannes Diderik van der Waals, the van der Waals force plays a fundamental role in fields as diverse as supramolecular chemistry, structural biology, polymer science, nanotechnology, surface science, and condensed matter physics. It also underlies many properties of organic compounds and molecular solids, including their solubility in polar and non-polar media. If no other force is present, the distance between atoms at which the force becomes repulsive rather than attractive as the atoms approach one another is called the va ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
WW Domain
The WW domain (also known as the rsp5-domain or WWP repeating structural motif, motif) is a modular protein domain that mediates specific interactions with protein ligands. This domain is found in a number of unrelated signaling and structural proteins and may be repeated up to four times in some proteins. Apart from binding preferentially to proteins that are proline-rich, with particular proline-motifs, [AP]-P-P-[AP]-Y, some WW domains bind to phosphoserine- and phosphothreonine-containing motifs. Structure and ligands The WW domain is one of the smallest protein modules, composed of only 40 amino acids, which mediates specific protein-protein interactions with short proline-rich or proline-containing motifs. Named after the presence of two conserved tryptophans (W), which are spaced 20-22 amino acids apart within the sequence, the WW domain folds into a meandering triple-stranded beta sheet. The identification of the WW domain was facilitated by the analysis of two splice ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Pin1
Peptidyl-prolyl cis-trans isomerase NIMA-interacting 1 is an enzyme that in humans is encoded by the ''PIN1'' gene. Pin 1, or peptidyl-prolyl cis/trans isomerase (PPIase), isomerizes only phospho-Serine/Threonine-Proline motifs. The enzyme binds to a subset of proteins and thus plays a role as a post phosphorylation control in regulating protein function. Studies have shown that the deregulation of Pin1 may play a pivotal role in various diseases. Notably, the up-regulation of Pin1 is implicated in certain cancers, and the down-regulation of Pin1 is implicated in Alzheimer's disease. Inhibitors of Pin1 may have therapeutic implications for cancer and immune disorders. Discovery The gene encoding Pin1 was identified in 1996 as a result of a genetic/biochemical screen for proteins involved in mitotic regulation. It was found to be essential for cell division in some organisms. By 1999, however, it was apparent that Pin1 knockout mice had a surprisingly mild phenotype, in ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Tryptophan
Tryptophan (symbol Trp or W) is an α-amino acid that is used in the biosynthesis of proteins. Tryptophan contains an α-amino group, an α-carboxylic acid group, and a side chain indole, making it a polar molecule with a non-polar aromatic beta carbon substituent. Tryptophan is also a precursor to the neurotransmitter serotonin, the hormone melatonin, and vitamin B3 (niacin). It is encoded by the codon UGG. Like other amino acids, tryptophan is a zwitterion at physiological pH where the amino group is protonated (–; pKa = 9.39) and the carboxylic acid is deprotonated ( –COO−; pKa = 2.38). Humans and many animals cannot synthesize tryptophan: they need to obtain it through their diet, making it an essential amino acid. Tryptophan is named after the digestive enzymes trypsin, which were used in its first isolation from casein proteins. It was assigned the one-letter symbol W based on the double ring being visually suggestive to the bulky letter. Function ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
