Portal:Chemistry
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 The binding of an inhibitor can stop a substrate from entering the enzyme's active site and/or hinder the enzyme from catalysing its reaction. Inhibitor binding is either reversible or irreversible. Irreversible inhibitors usually react with the enzyme and change it chemically. These inhibitors modify key amino acid residues needed for enzymatic activity. In contrast, reversible inhibitors bind non-covalently and different types of inhibition are produced depending on whether these inhibitors bind the enzyme, the enzyme-substrate complex, or both. Many drug molecules are enzyme inhibitors so their discovery and improvement is an active area of research in biochemistry and pharmacology. A medicinal enzyme inhibitor is often judged by its specificity (its lack of binding to other proteins) and its potency (its dissociation constant, which indicates the concentration needed to inhibit the enzyme). A high specificity and potency ensure that a drug will have few side effects and thus low toxicity. Enzyme inhibitors also occur naturally and are involved in the regulation of metabolism. For example, enzymes in a metabolic pathway can be inhibited by downstream products. This type of negative feedback slows flux through a pathway when the products begin to build up and is an important way to maintain homeostasis in a cell. Other cellular enzyme inhibitors are proteins that specifically bind to and inhibit an enzyme target. This can help control enzymes that may be damaging to a cell, such as proteases or nucleases; a well-characterised example is the ribonuclease inhibitor, which binds to ribonucleases in one of the tightest known protein–protein interactions. Natural enzyme inhibitors can also be poisons and are used as defences against predators or as ways of killing prey.  Malachite is a carbonate mineral, copper(II) carbonate hydroxide Cu2CO3(OH)2. It crystallizes in the monoclinic crystal system, and most often forms botryoidal, fibrous, or stalagmitic masses. Its beauty may be seen most strikingly in the Malachite Room at the Hermitage in Saint Petersburg. 
 Many chemists have an interest in the history of chemistry. Those with philosophical interests will be interested that the philosophy of chemistry has quite recently developed along a path somewhat different from the general philosophy of science. Other articles that might interest you are: There is a Wikipedia Project on the History of Science and portals for the scientific method and philosophy of science.  Wikipedia:WikiProject Chemicals/Data is a collection of links and references that are useful for chemistry-related works. This includes free online chemical databases, publications, patents, computer programs, and various tools. Science is Fun University of Wisconsin-Madison Chemistry Professor Bassam Z. Shakhashiri, shares the fun of science. megaConverter The Web's best place to figure out what equals what. General Chemistry Online Clear text and comprehensive coverage of general chemistry topics by Fred Senese, Dept. of Chemistry Frostburg State University General Chemistry Demonstration at Purdue Video clips (and descriptions) of lecture demonstrations. Intota Chemistry Experts A large online listing of real-world chemistry expert biographies provides examples of the many areas of expertise and careers in chemistry. Chemistry Webercises Directory A large listing of chemistry resources maintained by Steven Murov, Emeritus Chemistry Professor Modesto Junior College. MathMol MathMol (Mathematics and Molecules) is a good starting point for those interested in the field of molecular modeling. Chemistry Educational Resources and Essential References from Wiley, the world's largest chemistry publisher ABC Chemistry A directory of free full-text journals in chemistry, biochemistry and related subjects. Yuan Tseh Lee (born 1936) is a Taiwanese chemist, and the first Taiwanese-born Nobel Prize laureate. Along with John Charles Polanyi and Dudley R. Herschbach, he received the 1986 Nobel Prize in Chemistry "for their contributions to the dynamics of chemical elementary processes." Lee's particular work was on crossed molecular beams, to further its use in general reactions, a method for the study of important reactions for relatively large molecules. Since 1994, Lee has been the President of the Academia Sinica of the Republic of China.    Companies: AstraZeneca - Bayer - BP - BASF - Bristol Myers Squibb - Degussa - Dow - DuPont - ExxonMobil - GlaxoSmithKline - Mitsubishi - Monsanto - Nestlé - OSI - Shell - Sigma-Aldrich - Total
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