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Protein-tyrosine Phosphatase 1B
Tyrosine-protein phosphatase non-receptor type 1 also known as protein-tyrosine phosphatase 1B (PTP1B) is an enzyme that is the founding member of the protein tyrosine phosphatase (PTP) family. In humans it is encoded by the ''PTPN1'' gene. PTP1B is a negative regulator of the insulin signaling pathway and is considered a promising potential therapeutic target, in particular for treatment of type 2 diabetes. It has also been implicated in the development of breast cancer and has been explored as a potential therapeutic target in that avenue as well. Structure and function PTP1B was first isolated from a human placental protein extract, but it is expressed in many tissues. PTP1B is localized to the cytoplasmic face of the endoplasmic reticulum. PTP1B can dephosphorylate the phosphotyrosine residues of the activated insulin receptor kinase. In mice, genetic ablation of PTPN1 results in enhanced insulin sensitivity. Several other tyrosine kinases, including epidermal growth fa ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Enzyme
Enzymes () are proteins that act as biological catalysts by accelerating chemical reactions. The molecules upon which enzymes may act are called substrates, and the enzyme converts the substrates into different molecules known as products. Almost all metabolic processes in the cell need enzyme catalysis in order to occur at rates fast enough to sustain life. Metabolic pathways depend upon enzymes to catalyze individual steps. The study of enzymes is called ''enzymology'' and the field of pseudoenzyme analysis recognizes that during evolution, some enzymes have lost the ability to carry out biological catalysis, which is often reflected in their amino acid sequences and unusual 'pseudocatalytic' properties. Enzymes are known to catalyze more than 5,000 biochemical reaction types. Other biocatalysts are catalytic RNA molecules, called ribozymes. Enzymes' specificity comes from their unique three-dimensional structures. Like all catalysts, enzymes increase the reaction ra ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Pi Stacking
In chemistry, pi stacking (also called π–π stacking) refers to the presumptive attractive, noncovalent pi interactions (orbital overlap) between the pi bonds of aromatic rings. However this is a misleading description of the phenomena since direct stacking of aromatic rings (the "sandwich interaction") is electrostatically repulsive. What is more commonly observed (see figure to the right) is either a staggered stacking (parallel displaced) or pi-teeing (perpendicular T-shaped) interaction both of which are electrostatic attractive For example, the most commonly observed interactions between aromatic rings of amino acid residues in proteins is a staggered stacked followed by a perpendicular orientation. Sandwiched orientations are relatively rare. Pi stacking is repulsive as it places carbon atoms with partial negative charges from one ring on top of other partial negatively charged carbon atoms from the second ring and hydrogen atoms with partial positive charges on top ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Glutathione
Glutathione (GSH, ) is an antioxidant in plants, animals, fungi, and some bacteria and archaea. Glutathione is capable of preventing damage to important cellular components caused by sources such as reactive oxygen species, free radicals, peroxides, lipid peroxides, and heavy metals. It is a tripeptide with a gamma peptide linkage between the carboxyl group of the glutamate side chain and cysteine. The carboxyl group of the cysteine residue is attached by normal peptide linkage to glycine. Biosynthesis and occurrence Glutathione biosynthesis involves two adenosine triphosphate-dependent steps: *First, γ-glutamylcysteine is synthesized from L- glutamate and cysteine. This conversion requires the enzyme glutamate–cysteine ligase (GCL, glutamate cysteine synthase). This reaction is the rate-limiting step in glutathione synthesis. *Second, glycine is added to the C-terminal of γ-glutamylcysteine. This condensation is catalyzed by glutathione synthetase. While all animal ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Sulfenic Acid
In chemistry, a sulfenic acid is an organosulfur compound and oxoacid with the general formula . It is the first member of the family of organosulfur oxoacids, which also include sulfinic acids () and sulfonic acids (), respectively. The base member of the sulfenic acid series with R = H is hydrogen thioperoxide. Properties In contrast to sulfinic and sulfonic acids, simple sulfenic acids, such as methanesulfenic acid, CH3SOH, are highly reactive and cannot be isolated in solution. In the gas phase the lifetime of methanesulfenic acid is about one minute. The gas phase structure of methanesulfenic acid was found by microwave spectroscopy (rotational spectroscopy) to be CH3–S–O–H. Sulfenic acids can be stabilized through steric effects, which prevent the sulfenic acid from condensing with itself to form thiosulfinates, RS(O)SR, such as allicin from garlic. Through the use of X-ray crystallography, the structure of such stabilized sulfenic acids were shown to be R–S– ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Insulin
Insulin (, from Latin ''insula'', 'island') is a peptide hormone produced by beta cells of the pancreatic islets encoded in humans by the ''INS'' gene. It is considered to be the main anabolic hormone of the body. It regulates the metabolism of carbohydrates, fats and protein by promoting the absorption of glucose from the blood into liver, fat and skeletal muscle cells. In these tissues the absorbed glucose is converted into either glycogen via glycogenesis or fats (triglycerides) via lipogenesis, or, in the case of the liver, into both. Glucose production and secretion by the liver is strongly inhibited by high concentrations of insulin in the blood. Circulating insulin also affects the synthesis of proteins in a wide variety of tissues. It is therefore an anabolic hormone, promoting the conversion of small molecules in the blood into large molecules inside the cells. Low insulin levels in the blood have the opposite effect by promoting widespread catabolism, especially o ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Epidermal Growth Factor
Epidermal growth factor (EGF) is a protein that stimulates cell growth and differentiation by binding to its receptor, EGFR. Human EGF is 6-k Da and has 53 amino acid residues and three intramolecular disulfide bonds. EGF was originally described as a secreted peptide found in the submaxillary glands of mice and in human urine. EGF has since been found in many human tissues, including platelets, submandibular gland (submaxillary gland), and parotid gland. Initially, human EGF was known as urogastrone. Structure In humans, EGF has 53 amino acids (sequence NSDSECPLSHDGYCLHDGVCMYIEALDKYACNCVVGYIGERCQYRDLKWWELR), with a molecular mass of around 6 kDa. It contains three disulfide bridges (Cys6-Cys20, Cys14-Cys31, Cys33-Cys42). Function EGF, via binding to its cognate receptor, results in cellular proliferation, differentiation, and survival. Salivary EGF, which seems to be regulated by dietary inorganic iodine, also plays an important physiological role in the maintenance of ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Hydrogen Peroxide
Hydrogen peroxide is a chemical compound with the formula . In its pure form, it is a very pale blue liquid that is slightly more viscous than water. It is used as an oxidizer, bleaching agent, and antiseptic, usually as a dilute solution (3%–6% by weight) in water for consumer use, and in higher concentrations for industrial use. Concentrated hydrogen peroxide, or " high-test peroxide", decomposes explosively when heated and has been used as a propellant in rocketry. Hydrogen peroxide is a reactive oxygen species and the simplest peroxide, a compound having an oxygen–oxygen single bond. It decomposes slowly when exposed to light, and rapidly in the presence of organic or reactive compounds. It is typically stored with a stabilizer in a weakly acidic solution in a dark bottle to block light. Hydrogen peroxide is found in biological systems including the human body. Enzymes that use or decompose hydrogen peroxide are classified as peroxidases. Properties The boiling poi ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Reactive Oxygen Species
In chemistry, reactive oxygen species (ROS) are highly reactive chemicals formed from diatomic oxygen (). Examples of ROS include peroxides, superoxide, hydroxyl radical, singlet oxygen, and alpha-oxygen. The reduction of molecular oxygen () produces superoxide (), which is the precursor to most other reactive oxygen species: :O2 + e^- -> \ ^\bullet O2- Dismutation of superoxide produces hydrogen peroxide (): :2 H+ + \ ^\bullet O2^- + \ ^\bullet O2^- -> H2O2 + O2 Hydrogen peroxide in turn may be partially reduced, thus forming hydroxide ions and hydroxyl radicals (), or fully reduced to water: :H2O2 + e^- -> HO^- + \ ^\bullet OH :2 H+ + 2 e- + H2O2 -> 2 H2O In a biological context, ROS are byproducts of the normal metabolism of oxygen. ROS have roles in cell signaling and homeostasis. ROS are intrinsic to cellular functioning, and are present at low and stationary levels in normal cells. In plants, ROS are involved in metabolic processes related to photoprotection and toleran ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Protein Tyrosine Phosphatase
Protein tyrosine phosphatases (EC 3.1.3.48, systematic name protein-tyrosine-phosphate phosphohydrolase) are a group of enzymes that remove phosphate groups from phosphorylated tyrosine residues on proteins: : proteintyrosine phosphate + H2O = proteintyrosine + phosphate Protein tyrosine (pTyr) phosphorylation is a common post-translational modification that can create novel recognition motifs for protein interactions and cellular localization, affect protein stability, and regulate enzyme activity. As a consequence, maintaining an appropriate level of protein tyrosine phosphorylation is essential for many cellular functions. Tyrosine-specific protein phosphatases (PTPase; ) catalyse the removal of a phosphate group attached to a tyrosine residue, using a cysteinyl-phosphate enzyme intermediate. These enzymes are key regulatory components in signal transduction pathways (such as the MAP kinase pathway) and cell cycle control, and are important in the control of cell growth, ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
PTP1B Mechanism
Tyrosine-protein phosphatase non-receptor type 1 also known as protein-tyrosine phosphatase 1B (PTP1B) is an enzyme that is the founding member of the protein tyrosine phosphatase (PTP) family. In humans it is encoded by the ''PTPN1'' gene. PTP1B is a negative regulator of the insulin signaling pathway and is considered a promising potential therapeutic target, in particular for treatment of type 2 diabetes. It has also been implicated in the development of breast cancer and has been explored as a potential therapeutic target in that avenue as well. Structure and function PTP1B was first isolated from a human placental protein extract, but it is expressed in many tissues. PTP1B is localized to the cytoplasmic face of the endoplasmic reticulum. PTP1B can dephosphorylate the phosphotyrosine residues of the activated insulin receptor kinase. In mice, genetic ablation of PTPN1 results in enhanced insulin sensitivity. Several other tyrosine kinases, including epidermal growth factor r ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
