Chondroitin sulfate chains are unbranched polysaccharides of variable length containing two alternating monosaccharides: D-glucuronic acid (GlcA) and N-acetyl-D-galactosamine (GalNAc). Some GlcA residues are epimerized into L-iduronic acid (IdoA); the resulting disaccharide is then referred to as dermatan sulfate.
Chondroitin sulfate chains are linked to hydroxyl groups on serine residues of certain proteins. Exactly how proteins are selected for attachment of glycosaminoglycans is not understood. Glycosylated serines are often followed by a glycine and have neighboring acidic residues. But this does not always predict glycosylation.
Attachment of the GAG chain begins with four monosaccharides in a fixed pattern: Xyl - Gal - Gal - GlcA. Each sugar is attached by a specific enzyme, allowing for multiple levels of control over GAG synthesis. Xylose begins to be attached to proteins in the endoplasmic reticulum, while the rest of the sugars are attached in the Golgi apparatus.
Each monosaccharide may be left unsulfated, sulfated once, or sulfated twice. In the most common case, the hydroxyls of the 4 and 6 positions of the N-acetyl-galactosamine are sulfated, with some chains having the 2 position of glucuronic acid. Sulfation is mediated by specific sulfotransferases. Sulfation in these different positions gives specific biological activities to chondroitin GAG chains.
Chondroitin's functions depend largely on the properties of the overall proteoglycan of which it is a part. These functions can be broadly divided into structural and regulatory roles. Some proteoglycans have both structural and regulatory roles (see versican).
Chondroitin sulfate is a major component of extracellular matrix, and is important in maintaining the structural integrity of tissue. This function is typical of the large aggregating proteoglycans: aggrecan, versican, brevican, and neurocan, collectively termed the lecticans.
As part of aggrecan, chondroitin sulfate is a major component of cartilage. The tightly packed and highly charged sulfate groups of chondroitin sulfate generate electrostatic repulsion that provides much of the resistance of cartilage to compression. Loss of chondroitin sulfate from the cartilage is a major cause of osteoarthritis.
Chondroitin sulfate readily interacts with proteins in the extracellular matrix due to its negative charges. These interactions are important for regulating many cellular activities. The lecticans are a major part of the brain extracellular matrix, where the chondroitin sugar chains function to stabilize normal brain synapses as part of perineuronal nets. The levels of chondroitin sulfate proteoglycans are vastly increased after injury to the central nervous system where they act to prevent regeneration of damaged nerve endings. Although these functions are not as well characterized as those of heparan sulfate, new roles continue to be discovered for the chondroitin sulfate proteoglycans.
In cortical development, chondroitin sulfate is expressed by the Sub Plate and acts as a stop signal for neurons migrating from the Ventricular Zone. Neurons stopping here may then be programmed for further migration to specific layers in the cortical plate.
Chondroitin is in dietary supplements used as an alternative medicine to treat osteoarthritis and also approved and regulated as a symptomatic slow-acting drug for this disease (SYSADOA) in Europe and some other countries. It is commonly sold together with glucosamine. Chondroitin and glucosamine are also used in veterinary medicine.
Red Bull X2010
Red Bull X2010 is not a real car. It is a fictional car in the PlayStation 3 video game "Gran Turismo 5" that can go over 400 km/h, and over 6G's. It laps the Nürburgring in less than 4 minutes.. Adrian Newey designed it
Ireland (disambiguation)
Ireland may refer to:
Banbasa
Banbasa is the smallest town in Champawat district in Uttarakhand, India. The famous shri Purnagiri temple is only 35 km from here. It is near the Nepal border (Gaddachoki-Banbasa).
Velar consonant
A velar consonant is a consonant that is pronounced with the back part of the tongue against the soft palate, also known as the velum, which is the back part of the roof of the mouth. Velar consonants in English are , and . The consonant is the most common in all human languages.
These are the velar consonants in the IPA.
George Church
George Church (born August 28, 1954) is an American molecular geneticist. He was one of the people who set out to analyse the human genetic code, the sequence of genes in human DNA.
Church is Professor of Genetics at Harvard Medical School, Professor of Health Sciences and Technology at Harvard and MIT, and a core faculty member at the Wyss Institute for Biologically Inspired Engineering at Harvard University.
With Walter Gilbert he developed the first direct genomic sequencing method in 1984, and helped start the Human Genome Project in 1984 while he was a research scientist at newly formed Biogen Inc.
He invented ways of analysing huge amounts of chemical data, homologous recombination methods, and DNA array synthesizers. Automated sequencing & software in Genome Therapeutics Corp. gave the first commercial genome sequence, (the human pathogen, "Helicobacter pylori") in 1994.
Church started the Personal Genome Project (PGP) in 2005, and in 2007 he founded the U.S. personal genomics company Knome (with Jorge Conde and Sundar Subramaniam).
Church does research on synthetic (artificial) biology and is director of the U.S. Department of Energy Center on Bioenergy at Harvard & MIT, and Director of the National Institutes of Health Center of Excellence in Genomic Science at Harvard.
He has been advisor to 22 companies. He co-founded Codon Devices, a biotech startup dedicated to synthetic biology. It produces DNA sequences to order. He co-founded LS9, which is focused on biofuels or renewable petroleum technologies.
In 2009 he founded Pathogenica, with Yemi Adesokan, in order to pioneer commercial applications for pathogen sequencing technology.
In September 2010, Dr. Church was honored for his work in genetics with the Mass High Tech All-Star Award. He is a senior editor for "Molecular Systems Biology".
According to Forbes, Church suffers from narcolepsy.
Revolutions per minute
Revolutions per minute, sometimes called RPM, is a measure of angular frequency. It means the number of times something spins in one minute.
For example, if a wheel spins one time in one second, it is doing 60 RPM, because there is 60 seconds in one minute.
Walter Gilbert
Walter Gilbert (born March 21, 1932) is an American physicist, biochemist, molecular biology pioneer, and Nobel laureate. He helped develop DNA sequence analysis.
Gilbert was born in Boston, Massachusetts, on March 21, 1932. Gilbert attended Harvard University for undergraduate and graduate studies, earning a first degree in chemistry and physics in 1953 and a master's degree in physics in 1954.
Gilbert's doctoral work was done at the University of Cambridge, where he earned his PhD in mathematics under the mentorship of Nobel laureate Abdus Salam in 1957.
Gilbert returned to Harvard in 1957 and promoted in 1968 to professor of biochemistry. In 1969, Gilbert was given Harvard's Ledlie Prize. In 1972, Gilbert was named American Cancer Society Professor of Molecular Biology.
He is a co-founder of the biotech start-up companies Biogen and Myriad Genetics. Gilbert is currently the chairman of the Harvard Society of Fellows.
Together with Allan Maxam, Gilbert developed a new DNA sequencing method in 1976. With George Church he developed the first direct genomic sequencing method in 1984.
Gilbert first proposed the existence of introns and exons and explained the evolution of introns in a seminal 1978 "News and Views" paper published in "Nature". In 1986, Gilbert used the phrase RNA world hypothesis for the origin of life. 'RNA World' was a concept first proposed by Carl Woese in 1967.