Isoleucine is an α-amino acid, used in the biosynthesis of proteins. It contains an α-amino group, an α-carboxylic acid group, a hydrocarbon side chain with a branch, it is classified as a non-polar, branched-chain, aliphatic amino acid. It is essential in humans, meaning the body cannot synthesize it, must be ingested in our diet. Isoleucine is synthesized from pyruvate employing leucine biosynthesis enzymes in other organisms such as bacteria, it is encoded by the codons AUU, AUC, AUA. Inability to break down isoleucine, along with other amino acids, is associated with maple syrup urine disease; as an essential nutrient, it is not synthesized in the body, hence it must be ingested as a component of proteins. In plants and microorganisms, it is synthesized via several steps, starting from pyruvate and alpha-ketobutyrate. Enzymes involved in this biosynthesis include: Acetolactate synthase Acetohydroxy acid isomeroreductase Dihydroxyacid dehydratase Valine aminotransferase Isoleucine is both a glucogenic and a ketogenic amino acid.
After transamination with alpha-ketoglutarate the carbon skeleton is oxidised and split into propionyl-CoA and acetyl-CoA. Propionyl-CoA is converted into succinyl-CoA, a TCA cycle intermediate which can be converted into oxaloacetate for gluconeogenesis. In mammals acetyl-CoA cannot be converted to carbohydrate but can be either fed into the TCA cycle by condensing with oxaloacetate to form citrate or used in the synthesis of ketone bodies or fatty acids. Isoleucine, like other branched-chain amino acids, is associated with insulin resistance: higher levels of isoleucine are observed in the blood of diabetic mice and humans. Mice fed an isoleucine deprivation diet for one day have improved insulin sensitivity, feeding of an isoleucine deprivation diet for one week decreases blood glucose levels. In diet-induced obese and insulin resistant mice, a diet with decreased levels of isoleucine and the other branched-chain amino acids results in reduced adiposity and improved insulin sensitivity. In humans, a protein restricted diet lowers blood levels of isoleucine and decreases fasting blood glucose levels.
The Food and Nutrition Board of the U. S. Institute of Medicine set Recommended Dietary Allowances for essential amino acids in 2002. For isoleucine, for adults 19 years and older, 19 mg/kg body weight/day. Though this amino acid is not produced in animals, it is stored in high quantities. Foods that have high amounts of isoleucine include eggs, soy protein, turkey, lamb and fish. Isoleucine can be synthesized in a multistep procedure starting from 2-bromobutane and diethylmalonate. Synthetic isoleucine was reported in 1905 by French chemist Louis Bouveault. German chemist Felix Ehrlich discovered isoleucine in hemoglobin in 1903. Isoleucine and valine biosynthesis
The Lady Kirk at Pierowall is one of two ruined churches on the island of Westray, in Orkney, Scotland. It is a Scheduled Ancient Monument in the care of Historic Environment Scotland; the church was built on the foundations of the 13th-century church. The church is complete with the exception of the roof. Many of the walls stand to a high height, but some of it is 17th century built on the foundations of an earlier church; the south wall of the nave is from the original church. The nave altogether is rectangular, with a complete gable at its west end, topped off by a bellcote. A line of holes in the gable suggest there was a gallery at this end; the east end of the 1674 church formed a laird's aisle, erected on the site of the 13th-century chancel. The laird's aisle and the nave are separated by an arch that may have copied the earlier chancel arch. There are many different tomb stones in its graveyard, many with clear inscriptions. One example, located within the laird's aisle is a memorial in red marble to The memory of James Stewart of Bruce, the munificent donor of the Stewart Endowment, died 25 June 1858.
Nearby, in a transparent case to protect it from the elements is the large pink graveslab of Michael Balfour and others, dating back to 1657 and beautifully engraved. Next to it is another graveslab, of Helen Alexander, who died in 1676
The Mark 36 was a heavy high-yield United States nuclear bomb designed in the 1950s. It was a thermonuclear bomb, using a multi-stage fusion secondary system to generate yields up to about 10 megatons; the Mark 36 was a more advanced version of the earlier Mark 21 nuclear bomb, a weaponized version of the "Shrimp" design, the first "dry" fuel thermonuclear bomb the United States tested, in the Castle Bravo thermonuclear test in 1954. The Mark 21 bomb was developed and deployed after Castle Bravo, in 1955; the Mark 21 design continued to be improved and the Mark 36 device started production in April 1956. In 1957, all older Mark 21 bombs were converted to Mark 36 Y1 Mod 1 bombs. A total of 920 Mark 36 bombs were produced as new build or converted from the 275 Mark 21 bombs produced earlier. All Mark 36 nuclear bombs were retired between August 1961 and January 1962, replaced by the higher yield B41 nuclear bomb A Mark 36 casing is on display in the Cold War Gallery at the National Museum of the United States Air Force in Dayton, Ohio.
A Mark 36 casing can be found at the Strategic Space Museum near Ashland, Nebraska. A MK 36 can be found in the "Wings Over the Rockies" air museum in the Lowry neighborhood of Denver, Colorado; the Mark 36 bomb was 56.2 to 59 inches in diameter, depending on version, 150 inches long. It weighed 17,700 pounds depending on version. There were a "clean" and "dirty" variant; the clean variant used an inert fusion stage tamper-pusher assembly such as tungsten. The "dirty" variant used a depleted uranium or U-238 tamper-pusher which would undergo fission during the second stage fusion burn, doubling the weapon yield. Chuck Hansen wrote in Swords of Armageddon that Mark 36 nuclear bomb was produced in two yield versions and dirty, he stated that a clean version of a Mark 36 had a yield of 6 megatons and that a dirty version of a Mark 36 had a maximum yield of 19 megatons. List of nuclear weapons Teller-Ulam design Mark 21 nuclear bomb Hansen, Chuck, "Swords of Armageddon: U. S. Nuclear Weapons Development since 1945".
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