Enzymes are both proteins and biological catalysts. Catalysts accelerate chemical reactions; the molecules upon which enzymes may act are called substrates, the enzyme converts the substrates into different molecules known as products. 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 a new field of pseudoenzyme analysis has grown up, recognising that during evolution, some enzymes have lost the ability to carry out biological catalysis, 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 rate by lowering its activation energy; some enzymes can make their conversion of substrate to product occur many millions of times faster.
An extreme example is orotidine 5'-phosphate decarboxylase, which allows a reaction that would otherwise take millions of years to occur in milliseconds. Chemically, enzymes are like any catalyst and are not consumed in chemical reactions, nor do they alter the equilibrium of a reaction. Enzymes differ from most other catalysts by being much more specific. Enzyme activity can be affected by other molecules: inhibitors are molecules that decrease enzyme activity, activators are molecules that increase activity. Many therapeutic drugs and poisons are enzyme inhibitors. An enzyme's activity decreases markedly outside its optimal temperature and pH, many enzymes are denatured when exposed to excessive heat, losing their structure and catalytic properties; some enzymes are used commercially, in the synthesis of antibiotics. Some household products use enzymes to speed up chemical reactions: enzymes in biological washing powders break down protein, starch or fat stains on clothes, enzymes in meat tenderizer break down proteins into smaller molecules, making the meat easier to chew.
By the late 17th and early 18th centuries, the digestion of meat by stomach secretions and the conversion of starch to sugars by plant extracts and saliva were known but the mechanisms by which these occurred had not been identified. French chemist Anselme Payen was the first to discover an enzyme, diastase, in 1833. A few decades when studying the fermentation of sugar to alcohol by yeast, Louis Pasteur concluded that this fermentation was caused by a vital force contained within the yeast cells called "ferments", which were thought to function only within living organisms, he wrote that "alcoholic fermentation is an act correlated with the life and organization of the yeast cells, not with the death or putrefaction of the cells."In 1877, German physiologist Wilhelm Kühne first used the term enzyme, which comes from Greek ἔνζυμον, "leavened" or "in yeast", to describe this process. The word enzyme was used to refer to nonliving substances such as pepsin, the word ferment was used to refer to chemical activity produced by living organisms.
Eduard Buchner submitted his first paper on the study of yeast extracts in 1897. In a series of experiments at the University of Berlin, he found that sugar was fermented by yeast extracts when there were no living yeast cells in the mixture, he named the enzyme that brought about the fermentation of sucrose "zymase". In 1907, he received the Nobel Prize in Chemistry for "his discovery of cell-free fermentation". Following Buchner's example, enzymes are named according to the reaction they carry out: the suffix -ase is combined with the name of the substrate or to the type of reaction; the biochemical identity of enzymes was still unknown in the early 1900s. Many scientists observed that enzymatic activity was associated with proteins, but others argued that proteins were carriers for the true enzymes and that proteins per se were incapable of catalysis. In 1926, James B. Sumner crystallized it; the conclusion that pure proteins can be enzymes was definitively demonstrated by John Howard Northrop and Wendell Meredith Stanley, who worked on the digestive enzymes pepsin and chymotrypsin.
These three scientists were awarded the 1946 Nobel Prize in Chemistry. The discovery that enzymes could be crystallized allowed their structures to be solved by x-ray crystallography; this was first done for lysozyme, an enzyme found in tears and egg whites that digests the coating of some bacteria. This high-resolution structure of lysozyme marked the beginning of the field of structural biology and the effort to understand how enzymes work at an atomic level of detail. An enzyme's name is derived from its substrate or the chemical reaction it catalyzes, with the word ending in -ase. Examples are alcohol dehydrogenase and DNA polymerase. Different enzymes that catalyze the same chemical reaction are called isozymes; the International Union of Biochemistry and Molecular Biology have developed a nomenclature for enzymes, the EC numbers. The first number broadly classifies the enzyme based on its mechanism; the top-level classification is: EC 1, Oxidoreductases: catalyze oxidation/reduction reactions EC 2
Stagecoach is an unincorporated community and census-designated place in Lyon County, United States, located east of Reno. Its name is derived from its place as the Overland Stagecoach station at Desert Well; the mail, heading towards California was delivered on a steamship through Panama. But in 1857, the Overland mail company was created, the Desert Well station was a dual stop for both the stagecoach line and the Pony Express; as of the 2010 census, the population of Stagecoach was 1,874. Stagecoach is located along U. S. Route 50, 9 miles west of Silver Springs, 16 miles northeast of Dayton and 27 miles east of Carson City. According to the U. S. Census Bureau, the Stagecoach CDP has an area of 8.3 square miles, all land
Aleksey Nikolayevich Dudukalo is a Russian auto racing driver. He raced in the World Touring Car Championship between 2011 and 2013. Dudukalo started his racing career in 1995 in autocross racing. Five years he switched to single–seaters. Dudukalo competed in Russian Formula 1600, where he was third in 2004, he has successful in the Supertourism/Tourism 1600 and the Russian Honda Civic Cup/Super Light Cup, as well as the Touring-Light class of the Russian Touring Car Championship. In 2009 he finished 20th in the SEAT León Eurocup for Rangoni Motorsport, he competed in the SEAT León Supercopa with the same team. For 2010 Dudukalo switched to Sunred Engineering, he improved to seventh position in standings with a win at Brno. In 2011 Dudukalo moved up to the World Touring Car Championship, continuing his collaboration with SUNRED where he was joined by Gabriele Tarquini, he only finished the season 21st in the drivers' standings. Dudukalo was retained alongside Tarquini for 2012 with the team now run by Lukoil Racing.
He had qualified eighth for the Race of Spain. He qualified a career best second for the Race of Slovakia and finished in that position in race one behind his team mate to complete a Lukoil Racing Team 1–2, Dudukalo was the Yokohama Independents' Trophy winner; however race two saw Dudukalo issued with a drive through penalty as all four of his wheels were not on the ground when the five-minute board was shown on the grid. He started on pole position for race two of the Race of Austria but was overtaken at the start by the BMWs of Tom Coronel and Stefano D'Aste. Dudukalo was one of a few drivers, he clashed with former SEAT León Eurocup rival Gábor Wéber at the Race of Portugal and went into a gravel trap but both drivers were able to return to the pits. He clashed with ROAL Motorsport's Alberto Cerqui in race two of the Race of Brazil which caused Cerqui to crash into the pit wall. At the Race of the United States, having made it through to Q2 he beached his car near the end of the first session and brought the red flags out.
He was caught in a pileup at the start of race one which forced him to retire. A clash with Mehdi Bennani in the first race of the Race of Japan earned Dudukalo a 30–second post race penalty, he was classified fifteenth in the drivers' championship. Dudukalo will race alongside James Thompson at Lukoil Lada Sport in 2013. During qualifying for the Race of Italy Dudukalo missed the braking point for the first chicane and collided with his team–mate. Dudukalo was given a five–place grid drop for race one following the collision with Thompson. Lada withdrew both of their cars prior to the races as neither could be repaired in time to participate; the incident put Dudukalo's seat in doubt with the team considering bringing in a replacement driver. Prior to the Race of Morocco he was replaced at the team by Mikhail Kozlovskiy. Media related to Aleksei Dudukalo at Wikimedia Commons Profile at fiawtcc.com Aleksey Dudukalo career summary at DriverDB.com