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What Is The Chemical Composition Of Insulin?

Insulin

Insulin

The hormone insulin helps control the level of glucose in the blood A Molecular Messenger Our cells communicate using a molecular postal system: the blood is the postal service and hormones are the letters. Insulin is one of the most important hormones, carrying messages that describe the amount of sugar that is available from moment to moment in the blood. Insulin is made in the pancreas and added to the blood after meals when sugar levels are high. This signal then spreads throughout the body, binding to insulin receptors on the surface of liver, muscle and fat cells. Insulin tells these organs to take glucose out of the blood and store it, in the form of glycogen or fat. Folding Tiny Proteins Insulin is a tiny protein. It moves quickly through the blood and is easily captured by receptors on cell surfaces, delivering its message. Small proteins pose a challenge to cells: it is difficult to make a small protein that will fold into a stable structure. Our cells solve this problem by synthesizing a longer protein chain, which folds into the proper structure. Then, the extra piece is clipped away, leaving two small chains in the mature form. These two chains are shown in the lower diagram in blue and green, for insulin from pigs (PDB entry 4ins ). The structure is further stabilized by three disulfide bridges, one of which is seen in yellow in each illustration. Diabetes Mellitus When insulin function is impaired, either by damage to the pancreas or by the rigors of aging, glucose levels in the blood rise dangerously, leading to diabetes mellitus. For people totally deficient in insulin, such as children that develop diabetes early in life, this can be acutely dangerous. High glucose levels lead to dehydration, as the body attempts to flush out the excess sugar in urine, Continue reading >>

What Is Insulin?

What Is Insulin?

Insulin is a hormone that is important for metabolism and utilization of energy from the ingested nutrients - especially glucose. Insulin chemistry and etymology Insulin is a protein chain or peptide hormone. There are 51 amino acids in an insulin molecule. It has a molecular weight of 5808 Da. Insulin is produced in the islets of Langerhans in the pancreas. The name insulin comes from the Latin ''insula'' for "island" from the cells that produce the hormone in the pancreas. Insulin's structure varies slightly between species of animal. Both porcine (from pigs) and bovine (from cows) insulin are similar to human insulin but porcine insulin resembles human insulin more closely. What does insulin do? Insulin has several broad actions including: It causes the cells in the liver, muscle, and fat tissue to take up glucose from blood and convert it to glycogen that can be stored in the liver and muscles Insulin also prevents the utilization of fat as an energy source. In absence of insulin or in conditions where insulin is low glucose is not taken up by body cells, and the body begins to use fat as an energy source Insulin also controls other body systems and regulates the amino acid uptake by body cells It has several other anabolic effects throughout the body as well Secretion of insulin Insulin is synthesized in significant quantities only in beta cells in the pancreas. It is secreted primarily in response to elevated blood concentrations of glucose. Insulin thus can regulate blood glucose and the body senses and responds to rise in blood glucose by secreting insulin. Other stimuli like sight and taste of food, nerve stimulation and increased blood concentrations of other fuel molecules, including amino acids and fatty acids, also promote insulin secretion. What happens wh Continue reading >>

The Chemical Nature Of Insulin.

The Chemical Nature Of Insulin.

SAGE Video Streaming video collections SAGE Knowledge The ultimate social sciences library SAGE Research Methods The ultimate methods library SAGE Stats Data on Demand CQ Library American political resources About Privacy Policy Terms of Use Contact Us Help Health Sciences Life Sciences Materials Science & Engineering Social Sciences & Humanities Journals A-Z Authors Editors Reviewers Librarians Researchers Societies Advertising Reprints Content Sponsorships Permissions ISSN: 1535-3702 Online ISSN: 1535-3699 Continue reading >>

The Chemistry Of Insulin Apart

The Chemistry Of Insulin Apart

Introduction Insulin is an amazing drug that is used to help diabetic people live as healthy lives as they can. The drug is injected by syringe after a diabetic person eats, replacing the natural process that occurs in nondiabetic people, where insulin is transferred from the pancreas to the bloodstream into cells to take the new sugar and use it for energy or later use. Novolog, or insulin aspart, a specific type and brand of insulin, works in its own specific way. Insulin aspart is called rapid-acting insulin, in which the composition is manipulated from normal insulin to make it work faster. Insulin aspart starts to work 15 min after it is injected. I chose to do insulin, specifically insulin aspart, because I have been a type 1 diabetic for 8 years and use it everyday. Before researching, I was interested in how close man-made insulin was to human insulin, and it turns out that they are almost identical, being only one amino acid different. Insulin has always fascinated me. Insulin has affected my life in great ways. It is the single reason that I am still alive and healthy. Without it, especially insulin aspart, I do not even want to image what my life would look like, or what could ever take its place. Composition of ... C256H381N65O79S6 100 Units/mL Zinc = 19.6 mcg/mL Disodium hydrogen phosphate dihydrate = 1.25 mg/mL m-Cresol = 1.72 mg/mL Phenol = 1.5 mg/mL Glycerin = 16 mg/mL Sodium Chloride = .58 mg/mL Water = remainder for injection Main Chemicals, Compounds, Components Glycerin = C3H8O3 Glycerin is a simple sugar alcohol compound that is used in insulin as an isotonicity agent, or thing that makes insulin flow inside a body, like water. It is also a humectant, which means that it keeps insulin in liquid form for longer. Glycerin is a very important part of i Continue reading >>

Structure Of Insulin

Structure Of Insulin

Insulin is composed of two peptide chains referred to as the A chain and B chain. A and B chains are linked together by two disulfide bonds, and an additional disulfide is formed within the A chain. In most species, the A chain consists of 21 amino acids and the B chain of 30 amino acids. Although the amino acid sequence of insulin varies among species, certain segments of the molecule are highly conserved, including the positions of the three disulfide bonds, both ends of the A chain and the C-terminal residues of the B chain. These similarities in the amino acid sequence of insulin lead to a three dimensional conformation of insulin that is very similar among species, and insulin from one animal is very likely biologically active in other species. Indeed, pig insulin has been widely used to treat human patients. Insulin molecules have a tendency to form dimers in solution due to hydrogen-bonding between the C-termini of B chains. Additionally, in the presence of zinc ions, insulin dimers associate into hexamers. These interactions have important clinical ramifications. Monomers and dimers readily diffuse into blood, whereas hexamers diffuse poorly. Hence, absorption of insulin preparations containing a high proportion of hexamers is delayed and somewhat slow. This phenomenon, among others, has stimulated development of a number of recombinant insulin analogs. The first of these molecules to be marketed - called insulin lispro - is engineered such that lysine and proline residues on the C-terminal end of the B chain are reversed; this modification does not alter receptor binding, but minimizes the tendency to form dimers and hexamers. Send comments to [email protected] Continue reading >>

Facts About Diabetes And Insulin

Facts About Diabetes And Insulin

Diabetes is a very common disease, which, if not treated, can be very dangerous. There are two types of diabetes. They were once called juvenile-onset diabetes and adult diabetes. However, today we know that all ages can get both types so they are simply called type 1 and type 2 diabetes. Type 1, which occurs in approximately 10 percent of all cases, is an autoimmune disease in which the immune system, by mistake, attacks its own insulin-producing cells so that insufficient amounts of insulin are produced - or no insulin at all. Type 1 affects predominantly young people and usually makes its debut before the age of 30, and most frequently between the ages of 10 and 14. Type 2, which makes up the remaining 90 percent of diabetes cases, commonly affects patients during the second half of their lives. The cells of the body no longer react to insulin as they should. This is called insulin resistance. In the early 1920s, Frederick Banting, John Macleod, George Best and Bertram Collip isolated the hormone insulin and purified it so that it could be administered to humans. This was a major breakthrough in the treatment of diabetes type 1. Insulin Insulin is a hormone. Hormones are chemical substances that regulate the cells of the body and are produced by special glands. The hormone insulin is a main regulator of the glucose (sugar) levels in the blood. Insulin is produced in the pancreas. To be more specific, it's produced by the beta cells in the islets of Langerhans in the pancreas. When we eat, glucose levels rise, and insulin is released into the bloodstream. The insulin acts like a key, opening up cells so they can take in the sugar and use it as an energy source. Sugar is one of the top energy sources for the body. The body gets it in many forms, but mainly as carbohydr Continue reading >>

Insulin

Insulin

A protein with an impressive roster of ‘firsts’: Anna Lewcock introduces insulin Meera Senthilingam This week, a first for protein synthesis, resulting in a compound saving the lives of millions worldwide. Anna Lewcock… Anna Lewcock The year is 1922. Fourteen-year-old Leonard Thompson is at death’s door. Weighing just four and half stone, he is admitted to hospital slipping into a coma. In desperation, his father allows doctors to inject Leonard with a new drug never before tested on humans. But his son suffers an allergic reaction, and remains critically ill. Two weeks later, the doctors try again with a purer form of the extract. This time, the results are staggering. Leonard quickly regains his strength, his appetite, and his life. All thanks to a modest molecule called insulin. Insulin is a peptide hormone produced by the pancreas. But in the 371 million people worldwide who suffer from diabetes, something is amiss. In type 1 diabetes, the pancreas doesn’t produce any insulin. In the more common type 2, it doesn’t produce enough or the insulin it does produce doesn’t work properly. Insulin unlocks the body’s cells, allowing glucose in to be used for energy. With the body unable to metabolise glucose, it builds up in the blood leading to dangerously high blood sugar levels, and if left untreated, can lead to devastating health complications. Before the discovery of insulin, it was essentially a death sentence: patients with Type 1 diabetes were put on a starvation diet and given just months to live. Diabetes has been recognised as an illness for thousands of years. But it wasn’t until the late 1800s that researchers suggested we should look to the pancreas for a substance responsible for metabolic control. It then took until the 1920s for it to be i Continue reading >>

Insulin - An Overview | Sciencedirect Topics

Insulin - An Overview | Sciencedirect Topics

Insulin is a protein consisting of two polypeptide chains, A chain and B chain, linked together by disulfide bonds. Brian L. Furman, in xPharm: The Comprehensive Pharmacology Reference , 2007 Insulin is normally secreted rapidly from the beta-cells of the pancreatic islets in response to nutrients absorbed after a meal. In type 1 diabetes mellitus, there may be an absolute insulin deficiency as a consequence of autoimmune destruction of the beta-cells. On the other hand, in type 2 diabetes mellitus, insulin secretion is impaired and is inadequate to overcome peripheral insulin resistance. Insulin preparations are used to replace the deficient hormone in the treatment of diabetes, and currently, there is no alternative therapy for type 1 diabetes. Insulin is also to be used in the treatment of type 2 diabetes when this cannot be adequately controlled by orally active antidiabetic drugs. The aim of treatment using insulin is to maintain euglycemia (a plasma glucose level of 47 mmol/L) without causing hypoglycemia. There is much evidence that good control in both type 1 and type 2 diabetes will reduce the development of long-term microvascular and neuropathic complications of the disorder DCCT Research Group (1993), UK Prospective Diabetes Study Group (1998). However, good control is difficult to achieve because of the difficulty of administering insulin in a way that mimics physiological insulin secretion, with rapid peaks during and immediately after a meal and low, basal concentrations between meals. Insulin preparations are now largely based on human insulin prepared by enzymic modification of porcine insulin [human insulin (emp)], by chemical combination of the A and B chains produced using bacteria genetically modified by recombinant DNA technology [human insulin (c Continue reading >>

Insulin Protein Structure

Insulin Protein Structure

The structure of insulin is different among different species of animals. However, essentially it is a protein chain that is similar in many ways among animals. Human insulin is closest in structure and function with cow (bovine) or pig (porcine) insulin. Bovine insulin differs from human in only three amino acid residues, and porcine insulin in one. Insulin from some invertebrates and even fishes can be clinically useful in humans as they possess several similarities. Insulin structure Normal insulin that is biologically active is monomeric or exists as a single molecule. It has two long amino acid chains or polypeptide chains. The chains are chain A with 21 amino acids and chain B with 30 amino acids. Two disulfide bridges (residues A7 to B7, and A20 to B19) covalently connect the chains, and chain A contains an internal disulfide bridge (residues A6 to A11). These joints are similar in all mammalian forms of insulin. When secreted insulin joins in two’s to form dimmers and then in six’s to form hexamers. This combination takes place in the presence of zinc. The peptide chains then form 2 dimensional and three dimensional forms. Each of these 3-dimensional structures have three helices and three conserved disulfide bridges. This is a basic fold. This basic fold is present in all members of the insulin peptide family. At the core or center of the molecules is a hydrophobic or “water-hating” or water repellent area. These cluster of hydrophobic residues in the center contributes to protein stability. Stability is also lent by the disulfide bridges. Surrounding its core, the monomer has two extensive nonpolar surfaces. One of them is a flat one that is aromatic and gets buried when there is a dimer formation. The other surface is more extensive and disappears whe Continue reading >>

History Of Insulin

History Of Insulin

Rosie Cotter explores the history of this important protein and its role in diabetes In 1922, a 14-year-old boy named Leonard Thompson lay in Toronto General Hospital dying from diabetes. He weighed less than 30 kg and was at risk of slipping into a diabetic coma. To avoid this, Leonard’s father allowed him to be injected with a new pancreatic extract, now known as insulin. At the time, people with diabetes tried to control their condition through a strict diet, but they usually died within a year of diagnosis. Remarkably, after the injection, Leonard regained his strength and appetite and went on to live for several more years. News of insulin and Leonard’s recovery spread around the world and brought notoriety to Dr Frederick Banting and student George Best at the University of Toronto. With the support of Professor John Macleod and biochemist Bertram Collip, Banting and Best had successfully extracted insulin from an animal pancreas and purified it so that it could be administered to humans. Insulin is a hormone that regulates glucose levels in the blood. When we eat, our glucose levels rise and insulin is released into the bloodstream. Insulin works by regulating glucose transport proteins in cells so they can take up the glucose and use it as an energy source or convert it to glycogen for storage. Type 1 diabetes develops when the insulin-producing beta cells of the islets of Langerhans found in the pancreas have been destroyed and the body is unable to produce insulin. Type 2 diabetes develops when the body can still make some insulin, but it is produced in insufficient amounts or in a form that does not work properly. Discovery and application Between 1920 and 1921, Banting and Best had been removing dogs’ pancreases to make them diabetic. Building on the w Continue reading >>

Molecule Of The Month - July 2010

Molecule Of The Month - July 2010

Computer-generated image of six insulin molecules assembled in a hexamer (from Ref.[1]). 3D structure file INSULIN The hormone that converts sugar in the blood into asource of energy for our body's metabolic processes "Laughter is the best medicine- unless you're diabetic, then insulin comes pretty high on the list" - Jasper Carrott [3] So, what is a hormone, really? Hormones are chemical components that are produced in one part of the body and function at an entirely different one [4]. They include proteins, peptides and lipids, existing usually as precursor molecules [5]. In addition hormones have various functions such as the regulation of metabolism and its development. A major role is to act as messengers and carry information around tissues in the body by binding receptors on cell surfaces or within a cell [5]. Receptors are proteins on cell surfaces or within them with available sites for the signalling ligand molecule to bind on. The receptor's major role is to act as the conductor for hormones and drugs to reach the body and the target they require. One of the main peptide hormones studied through years due to its importance and necessity is insulin, whose structure, synthesis and function are discussed further below. What does insulin do? Insulin is a hormone that is central to regulating glucose metabolism in the body to produce energy. Insulin causes cells in the liver, muscle, and fat tissue to take up glucose from the blood, which it then converts to glycogen which is stored in the liver and muscle. When insulin is absent, glucose is not taken up by body cells and the body begins to use fat as an energy source. What about insulin's structure? It seems to be very complicated. Insulin is a peptide hormone composed of 51 amino acids and has a molecular weight Continue reading >>

Insulin

Insulin

Insulin, hormone that regulates the level of sugar (glucose) in the blood and that is produced by the beta cells of the islets of Langerhans in the pancreas. Insulin is secreted when the level of blood glucose rises—as after a meal. When the level of blood glucose falls, secretion of insulin stops, and the liver releases glucose into the blood. Insulin was first reported in pancreatic extracts in 1921, having been identified by Canadian scientists Frederick G. Banting and Charles H. Best and by Romanian physiologist Nicolas C. Paulescu, who was working independently and called the substance “pancrein.” After Banting and Best isolated insulin, they began work to obtain a purified extract, which they accomplished with the help of Scottish physiologist J.J.R. Macleod and Canadian chemist James B. Collip. Banting and Macleod shared the 1923 Nobel Prize for Physiology or Medicine for their work. Insulin is a protein composed of two chains, an A chain (with 21 amino acids) and a B chain (with 30 amino acids), which are linked together by sulfur atoms. Insulin is derived from a 74-amino-acid prohormone molecule called proinsulin. Proinsulin is relatively inactive, and under normal conditions only a small amount of it is secreted. In the endoplasmic reticulum of beta cells the proinsulin molecule is cleaved in two places, yielding the A and B chains of insulin and an intervening, biologically inactive C peptide. The A and B chains become linked together by two sulfur-sulfur (disulfide) bonds. Proinsulin, insulin, and C peptide are stored in granules in the beta cells, from which they are released into the capillaries of the islets in response to appropriate stimuli. These capillaries empty into the portal vein, which carries blood from the stomach, intestines, and pancrea Continue reading >>

Insulin, Chemical Structure And Metabolism

Insulin, Chemical Structure And Metabolism

Insulin is a polypeptide hormone formed, after elimination of C peptide by hydrolysis, of two chains of 21 and 30 amino acids, connected by two disulfide bridges. It is secreted by the ß cells of the islets of Langerhans of the pancreas and exerts an hypoglycemic action. It belongs to the group of peptides called IGF (insulin like growth factors) or somatomedins. Biosynthesis Insulin is produced in beta cells which constitute 75% of the islets of Langerhans of the pancreas. Alpha cells secrete glucagon, delta cells somatostatin. Insulin is synthesized in the form of a single polypeptide chain, preproinsulin which is transformed into proinsulin which, itself, catalyzed by proteases called furines, gives insulin and C peptide (C for connecting, because connecting the two chains A and B). Bound to two zinc atoms, insulin is stored in granules as a polymer, probably a hexamer. Secretion Insulin, as well as C peptide, are released by exocytosis into the portal venous system which leads it directly to the liver, which takes up nearly 50%. The remainder of insulin is distributed throughout the body. With a basal secretion of approximately 40 microgram/h under fasting conditions, there are increases of secretion linked to meals. To these slow variations are superimposed peaks of pulsatile secretion. The aim of the treatments by exogenous insulin is to approach the physiological curve of secretion. The principal stimulant of insulin secretion is glucose; it elicits a biphasic release: an immediate effect of short duration and a sustained effect. The cells of the islets are connected by tight junctions, which allow the transfer of ions, of metabolites, secondary messengers from one cell to another, and thus play an important part in synchronizing the secretions. The stimulation Continue reading >>

The Chemistry And Biochemistry Of Insulin

The Chemistry And Biochemistry Of Insulin

The Chemistry and Biochemistry of Insulin Please review our Terms and Conditions of Use and check box below to share full-text version of article. I have read and accept the Wiley Online Library Terms and Conditions of Use. Use the link below to share a full-text version of this article with your friends and colleagues. Learn more. Get access to the full version of this article. View access options below. You previously purchased this article through ReadCube. View access options below. Purchase options have been disabled temporarily. Please try again later. The protein hormone insulin occurs widely in the animal kingdom. Although its biological function is always the same, its aminoacid composition varies widely. Insulin consists of two polypeptide chains, which are linked by three cystine residues to form a bicyclic system with a 20membered and an 85membered ring. The protein crystallizes in various forms with foreign ions. In solution, insulin normally forms aggregates of 2n molecules. The hormone can be regenerated from the separated polypeptide chains, and its total synthesis has been achieved in a similar manner from synthesized peptide chains. In the biosynthesis of insulin, the two chains are evidently built up separately and subsequently linked together. Insulin promotes the synthesis of glycogen, fat, and protein in the organism; insulin deficiency leads to an increase in the bloodsugar level. At the molecular level, the mechanism of action of the hormone is still unknown. Current hypotheses are discussed. No specific active center has so far been detected in the insulin molecule, which contains several antigenic regions. Continue reading >>

How Insulin Is Made - Material, Manufacture, History, Used, Parts, Components, Structure, Steps, Product

How Insulin Is Made - Material, Manufacture, History, Used, Parts, Components, Structure, Steps, Product

Background Insulin is a hormone that regulates the amount of glucose (sugar) in the blood and is required for the body to function normally. Insulin is produced by cells in the pancreas, called the islets of Langerhans. These cells continuously release a small amount of insulin into the body, but they release surges of the hormone in response to a rise in the blood glucose level. Certain cells in the body change the food ingested into energy, or blood glucose, that cells can use. Every time a person eats, the blood glucose rises. Raised blood glucose triggers the cells in the islets of Langerhans to release the necessary amount of insulin. Insulin allows the blood glucose to be transported from the blood into the cells. Cells have an outer wall, called a membrane, that controls what enters and exits the cell. Researchers do not yet know exactly how insulin works, but they do know insulin binds to receptors on the cell's membrane. This activates a set of transport molecules so that glucose and proteins can enter the cell. The cells can then use the glucose as energy to carry out its functions. Once transported into the cell, the blood glucose level is returned to normal within hours. Without insulin, the blood glucose builds up in the blood and the cells are starved of their energy source. Some of the symptoms that may occur include fatigue, constant infections, blurred eye sight, numbness, tingling in the hands or legs, increased thirst, and slowed healing of bruises or cuts. The cells will begin to use fat, the energy source stored for emergencies. When this happens for too long a time the body produces ketones, chemicals produced by the liver. Ketones can poison and kill cells if they build up in the body over an extended period of time. This can lead to serious illne Continue reading >>

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