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Phosphothreonine
Threonine (symbol Thr or T) is an amino acid that is used in the biosynthesis of proteins. It contains an α-amino group (which is in the protonated −NH form when dissolved in water), a carboxyl group (which is in the deprotonated −COO− form when dissolved in water), and a side chain containing a hydroxyl group, making it a polar, uncharged amino acid. It is essential in humans, meaning the body cannot synthesize it: it must be obtained from the diet. Threonine is synthesized from aspartate in bacteria such as ''E. coli''. It is encoded by all the codons starting AC (ACU, ACC, ACA, and ACG). Threonine sidechains are often hydrogen bonded; the most common small motifs formed are based on interactions with serine: ST turns, ST motifs (often at the beginning of alpha helices) and ST staples (usually at the middle of alpha helices). Modifications The threonine residue is susceptible to numerous posttranslational modifications. The hydroxyl side-chain can undergo ''O''- ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Posttranslational Modification
In molecular biology, post-translational modification (PTM) is the covalent process of changing proteins following protein biosynthesis. PTMs may involve enzymes or occur spontaneously. Proteins are created by ribosomes, which translate mRNA into polypeptide chains, which may then change to form the mature protein product. PTMs are important components in cell signalling, as for example when prohormones are converted to hormones. Post-translational modifications can occur on the amino acid side chains or at the protein's C- or N- termini. They can expand the chemical set of the 22 amino acids by changing an existing functional group or adding a new one such as phosphate. Phosphorylation is highly effective for controlling the enzyme activity and is the most common change after translation. Many eukaryotic and prokaryotic proteins also have carbohydrate molecules attached to them in a process called glycosylation, which can promote protein folding and improve stability a ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Skeletal Formula
The skeletal formula, line-angle formula, bond-line formula or shorthand formula of an organic compound is a type of minimalist structural formula representing a molecule's Atom, atoms, structural isomer, bonds and some details of its molecular geometry, geometry. The lines in a skeletal formula represent bonds between carbon atoms, unless labelled with another element. Labels are optional for carbon atoms, and the hydrogen atoms attached to them. An early form of this representation was first developed by organic chemist August Kekulé, while the modern form is closely related to and influenced by the Lewis structure of molecules and their valence electrons. Hence they are sometimes termed Kekulé structures or Lewis–Kekulé structures. Skeletal formulas have become ubiquitous in organic chemistry, partly because they are relatively quick and simple to draw, and also because the Arrow pushing, curved arrow notation used for discussions of reaction mechanisms and Resonance ( ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
ST Turn
The ST turn is a structural feature in proteins and polypeptides. Each consists of three amino acid residues (labeled ''i'', ''i'' + 1 and ''i'' + 2) in which residue ''i'' is a serine (S) or threonine (T) that forms a hydrogen bond from its sidechain oxygen group to the mainchain NH group of residue ''i'' + 2. Similar Structural motif, motifs occur with aspartate or asparagine as residue ''i'', called asx turn. Four types of asx turn and ST turn can be distinguished: types I, I’, II and II’. These categories correspond (via sidechain-mainchain mimicry of residue i) to those of the more abundant hydrogen-bonded beta turns, which have four residues and a hydrogen bond between the CO of residue ''i'' and the NH of residue ''i'' + 3. Regarding their occurrence in proteins, they differ in that type I is the commonest of the four beta turns while type II’ is the commonest of the ST and asx turns. Asx and ST turns both occur frequently at th ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
William Cumming Rose
William Cumming Rose (April 4, 1887 – September 25, 1985) was an American biochemist and nutritionist. He discovered the amino acid threonine, and his research determined the necessity for essential amino acids in diet and the minimum daily requirements of all amino acids for optimal growth. Early life William Cumming Rose was born in Greenville, South Carolina. He attended various local schools, but his father John M. Rose, who was a Presbyterian minister, began to homeschool William in Latin, Greek, and Hebrew when he was 14 years old. He also studied an introductory chemistry textbook by Ira Remsen. When he was 16, he studied at Davidson College in North Carolina for his bachelor's degree. He took up graduate education at Yale University studying food chemistry with Russell Chittenden and Lafayette Mendel. He was granted a PhD in 1911. Career Rose taught for a time at University of Pennsylvania with Alonzo E. Taylor. Taylor recommended him to University of Texas Galves ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Proteinogenic
Proteinogenic amino acids are amino acids that are incorporated biosynthetically into proteins during translation from RNA. The word "proteinogenic" means "protein creating". Throughout known life, there are 22 genetically encoded (proteinogenic) amino acids, 20 in the standard genetic code and an additional 2 (selenocysteine and pyrrolysine) that can be incorporated by special translation mechanisms. In contrast, non-proteinogenic amino acids are amino acids that are either not incorporated into proteins (like GABA, L-DOPA, or triiodothyronine), misincorporated in place of a genetically encoded amino acid, or not produced directly and in isolation by standard cellular machinery (like hydroxyproline). The latter often results from post-translational modification of proteins. Some non-proteinogenic amino acids are incorporated into nonribosomal peptides which are synthesized by non-ribosomal peptide synthetases. Both eukaryotes and prokaryotes can incorporate selenocysteine into ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Metal
A metal () is a material that, when polished or fractured, shows a lustrous appearance, and conducts electrical resistivity and conductivity, electricity and thermal conductivity, heat relatively well. These properties are all associated with having electrons available at the Fermi level, as against nonmetallic materials which do not. Metals are typically ductile (can be drawn into a wire) and malleable (can be shaped via hammering or pressing). A metal may be a chemical element such as iron; an alloy such as stainless steel; or a molecular compound such as polythiazyl, polymeric sulfur nitride. The general science of metals is called metallurgy, a subtopic of materials science; aspects of the electronic and thermal properties are also within the scope of condensed matter physics and solid-state chemistry, it is a multidisciplinary topic. In colloquial use materials such as steel alloys are referred to as metals, while others such as polymers, wood or ceramics are nonmetallic ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Ligand
In coordination chemistry, a ligand is an ion or molecule with a functional group that binds to a central metal atom to form a coordination complex. The bonding with the metal generally involves formal donation of one or more of the ligand's electron pairs, often through Lewis acids and bases, Lewis bases. The nature of metal–ligand bonding can range from covalent bond, covalent to ionic bond, ionic. Furthermore, the metal–ligand bond order can range from one to three. Ligands are viewed as Lewis bases, although rare cases are known to involve Lewis acids and bases, Lewis acidic "ligands". Metals and metalloids are bound to ligands in almost all circumstances, although gaseous "naked" metal ions can be generated in a high vacuum. Ligands in a complex dictate the reactivity (chemistry), reactivity of the central atom, including ligand substitution rates, the reactivity of the ligands themselves, and redox. Ligand selection requires critical consideration in many practical are ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Protein Kinase
A protein kinase is a kinase which selectively modifies other proteins by covalently adding phosphates to them ( phosphorylation) as opposed to kinases which modify lipids, carbohydrates, or other molecules. Phosphorylation usually results in a functional change of the target protein ( substrate) by changing enzyme activity, cellular location, or association with other proteins. The human genome contains about 500 protein kinase genes and they constitute about 2% of all human genes. There are two main types of protein kinase. The great majority are serine/threonine kinases, which phosphorylate the hydroxyl groups of serines and threonines in their targets. Most of the others are tyrosine kinases, although additional types exist. Protein kinases are also found in bacteria and plants. Up to 30% of all human proteins may be modified by kinase activity, and kinases are known to regulate the majority of cellular pathways, especially those involved in signal transduction. Chemical ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Phosphorylation
In biochemistry, phosphorylation is described as the "transfer of a phosphate group" from a donor to an acceptor. A common phosphorylating agent (phosphate donor) is ATP and a common family of acceptor are alcohols: : This equation can be written in several ways that are nearly equivalent that describe the behaviors of various protonated states of ATP, ADP, and the phosphorylated product. As is clear from the equation, a phosphate group per se is not transferred, but a phosphoryl group (PO3-). Phosphoryl is an electrophile. This process and its inverse, dephosphorylation, are common in biology. Text was copied from this source, which is available under a Creative Commons Attribution 4.0 International License. Protein phosphorylation often activates (or deactivates) many enzymes. During respiration Phosphorylation is essential to the processes of both anaerobic and aerobic respiration, which involve the production of adenosine triphosphate (ATP), the "high-energy" exc ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
O-linked Glycosylation
''O''-linked glycosylation is the attachment of a sugar molecule to the oxygen atom of serine (Ser) or threonine (Thr) residues in a protein. ''O''-glycosylation is a post-translational modification that occurs after the protein has been synthesised. In eukaryotes, it occurs in the endoplasmic reticulum, Golgi apparatus and occasionally in the cytoplasm; in prokaryotes, it occurs in the cytoplasm. Several different sugars can be added to the serine or threonine, and they affect the protein in different ways by changing protein stability and regulating protein activity. O-glycans, which are the sugars added to the serine or threonine, have numerous functions throughout the body, including trafficking of cells in the immune system, allowing recognition of foreign material, controlling cell metabolism and providing cartilage and tendon flexibility. Because of the many functions they have, changes in O-glycosylation are important in many diseases including cancer, diabetes and Alzheime ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Side Chain
In organic chemistry and biochemistry, a side chain is a substituent, chemical group that is attached to a core part of the molecule called the "main chain" or backbone chain, backbone. The side chain is a hydrocarbon branching element of a molecule that is attached to a larger hydrocarbon backbone. It is one factor in determining a molecule's properties and reactivity. A side chain is also known as a pendant chain, but a pendant group (side group) has a different definition. Conventions The placeholder R is often used as a generic placeholder for alkyl (saturated hydrocarbon) group side chains in structural formulae. To indicate other non-carbon groups in structure diagrams, X, Y, or Z are often used. History The ''R'' symbol was introduced by 19th-century French chemist Charles Frédéric Gerhardt, who advocated its adoption on the grounds that it would be widely recognizable and intelligible given its correspondence in multiple European languages to the initial letter of "r ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Hydroxyl
In chemistry, a hydroxy or hydroxyl group is a functional group with the chemical formula and composed of one oxygen atom covalently bonded to one hydrogen atom. In organic chemistry, alcohols and carboxylic acids contain one or more hydroxy groups. Both the negatively charged anion , called hydroxide, and the neutral radical , known as the hydroxyl radical, consist of an unbonded hydroxy group. According to IUPAC definitions, the term ''hydroxyl'' refers to the hydroxyl radical () only, while the functional group is called a ''hydroxy group''. Properties Water, alcohols, carboxylic acids, and many other hydroxy-containing compounds can be readily deprotonated due to a large difference between the electronegativity of oxygen (3.5) and that of hydrogen (2.1). Hydroxy-containing compounds engage in intermolecular hydrogen bonding increasing the electrostatic attraction between molecules and thus to higher boiling and melting points than found for compounds that lack thi ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
