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Holocarboxylase Synthetase
Holocarboxylase synthetase (biotin—(propionyl-Coenzyme A-carboxylase (ATP-hydrolysing)) ligase)), also known as protein—biotin ligase, is a family of enzymes (). This enzyme is important for the effective use of biotin, a B vitamin found in foods such as liver, egg yolks, and milk. In many of the body's tissues, holocarboxylase synthetase activates other specific enzymes (called biotin-dependent carboxylases) by attaching biotin to them. These carboxylases are involved in many critical cellular functions, including the production and breakdown of proteins, fats, and carbohydrates. The catalyzed reaction: :ATP + biotin + apo- propionyl-CoA:carbon-dioxide ligase (ADP-forming) \rightleftharpoons AMP + diphosphate + propionyl-CoA:carbon-dioxide ligase (ADP-forming) The 3 substrates of this enzyme are ATP, biotin, and AMP, diphosphate, and propionyl-CoA:carbon-dioxide ligase (ADP-forming). Holocarboxylase synthetase may also play a role in regulating the activity of gen ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Biotin
Biotin (also known as vitamin B7 or vitamin H) is one of the B vitamins. It is involved in a wide range of metabolic processes, both in humans and in other organisms, primarily related to the utilization of fats, carbohydrates, and amino acids. The name ''biotin'', borrowed from the German , derives from the Ancient Greek word (; 'life') and the suffix "-in" (a suffix used in chemistry usually to indicate 'forming'). Biotin appears as a white, needle-like crystalline solid. Chemical description Biotin is classified as a heterocyclic compound, with a sulfur-containing tetrahydrothiophene ring fused to a ureido group. A C5-carboxylic acid side chain is appended to the former ring. The ureido ring, containing the −N−CO−N− group, serves as the carbon dioxide carrier in carboxylation reactions. Biotin is a coenzyme for five carboxylase enzymes, which are involved in the catabolism of amino acids and fatty acids, synthesis of fatty acids, and gluconeogenesis. Biotinylat ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Base Pair
A base pair (bp) is a fundamental unit of double-stranded nucleic acids consisting of two nucleobases bound to each other by hydrogen bonds. They form the building blocks of the DNA double helix and contribute to the folded structure of both DNA and RNA. Dictated by specific hydrogen bonding patterns, "Watson–Crick" (or "Watson–Crick–Franklin") base pairs (guanine–cytosine and adenine–thymine) allow the DNA helix to maintain a regular helical structure that is subtly dependent on its nucleotide sequence. The Complementarity (molecular biology), complementary nature of this based-paired structure provides a Redundancy (information theory), redundant copy of the genetic information encoded within each strand of DNA. The regular structure and data redundancy provided by the DNA double helix make DNA well suited to the storage of genetic information, while base-pairing between DNA and incoming nucleotides provides the mechanism through which DNA polymerase replicates DNA and ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Biotinylation
In biochemistry, biotinylation is the process of covalently attaching biotin to a protein, nucleic acid or other molecule. Biotinylation is rapid, specific and is unlikely to disturb the natural function of the molecule due to the small size of biotin (MW = 244.31 g/mol). Biotin binds to streptavidin and avidin with an extremely high affinity, fast on-rate, and high specificity, and these interactions are exploited in many areas of biotechnology to isolate biotinylated molecules of interest. Biotin-binding to streptavidin and avidin is resistant to extremes of heat, pH and proteolysis, making capture of biotinylated molecules possible in a wide variety of environments. Also, multiple biotin molecules can be Cross-link, conjugated to a protein of interest, which allows binding of multiple streptavidin, avidin or neutravidin protein molecules and increases the sensitivity of detection of the protein of interest. There is a large number of biotinylation reagents available that expl ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Carbohydrate
A carbohydrate () is a biomolecule composed of carbon (C), hydrogen (H), and oxygen (O) atoms. The typical hydrogen-to-oxygen atomic ratio is 2:1, analogous to that of water, and is represented by the empirical formula (where ''m'' and ''n'' may differ). This formula does not imply direct covalent bonding between hydrogen and oxygen atoms; for example, in , hydrogen is covalently bonded to carbon, not oxygen. While the 2:1 hydrogen-to-oxygen ratio is characteristic of many carbohydrates, exceptions exist. For instance, uronic acids and deoxy-sugars like fucose deviate from this precise stoichiometric definition. Conversely, some compounds conforming to this definition, such as formaldehyde and acetic acid, are not classified as carbohydrates. The term is predominantly used in biochemistry, functioning as a synonym for saccharide (), a group that includes sugars, starch, and cellulose. The saccharides are divided into four chemical groups: monosaccharides, disaccharides, ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Protein
Proteins are large biomolecules and macromolecules that comprise one or more long chains of amino acid residue (biochemistry), residues. Proteins perform a vast array of functions within organisms, including Enzyme catalysis, catalysing metabolic reactions, DNA replication, Cell signaling, responding to stimuli, providing Cytoskeleton, structure to cells and Fibrous protein, organisms, and Intracellular transport, transporting molecules from one location to another. Proteins differ from one another primarily in their sequence of amino acids, which is dictated by the Nucleic acid sequence, nucleotide sequence of their genes, and which usually results in protein folding into a specific Protein structure, 3D structure that determines its activity. A linear chain of amino acid residues is called a polypeptide. A protein contains at least one long polypeptide. Short polypeptides, containing less than 20–30 residues, are rarely considered to be proteins and are commonly called pep ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Histone
In biology, histones are highly basic proteins abundant in lysine and arginine residues that are found in eukaryotic cell nuclei and in most Archaeal phyla. They act as spools around which DNA winds to create structural units called nucleosomes. Nucleosomes in turn are wrapped into 30- nanometer fibers that form tightly packed chromatin. Histones prevent DNA from becoming tangled and protect it from DNA damage. In addition, histones play important roles in gene regulation and DNA replication. Without histones, unwound DNA in chromosomes would be very long. For example, each human cell has about 1.8 meters of DNA if completely stretched out; however, when wound about histones, this length is reduced to about 9 micrometers (0.09 mm) of 30 nm diameter chromatin fibers. There are five families of histones, which are designated H1/H5 (linker histones), H2, H3, and H4 (core histones). The nucleosome core is formed of two H2A-H2B dimers and a H3-H4 tetramer. The tight wr ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Amino Acid
Amino acids are organic compounds that contain both amino and carboxylic acid functional groups. Although over 500 amino acids exist in nature, by far the most important are the 22 α-amino acids incorporated into proteins. Only these 22 appear in the genetic code of life. Amino acids can be classified according to the locations of the core structural functional groups ( alpha- , beta- , gamma- amino acids, etc.); other categories relate to polarity, ionization, and side-chain group type ( aliphatic, acyclic, aromatic, polar, etc.). In the form of proteins, amino-acid '' residues'' form the second-largest component (water being the largest) of human muscles and other tissues. Beyond their role as residues in proteins, amino acids participate in a number of processes such as neurotransmitter transport and biosynthesis. It is thought that they played a key role in enabling life on Earth and its emergence. Amino acids are formally named by the IUPAC- IUBMB Joint Commi ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Mutation
In biology, a mutation is an alteration in the nucleic acid sequence of the genome of an organism, virus, or extrachromosomal DNA. Viral genomes contain either DNA or RNA. Mutations result from errors during DNA or viral replication, mitosis, or meiosis or other types of damage to DNA (such as pyrimidine dimers caused by exposure to ultraviolet radiation), which then may undergo error-prone repair (especially microhomology-mediated end joining), cause an error during other forms of repair, or cause an error during replication ( translesion synthesis). Mutations may also result from substitution, insertion or deletion of segments of DNA due to mobile genetic elements. Mutations may or may not produce detectable changes in the observable characteristics ( phenotype) of an organism. Mutations play a part in both normal and abnormal biological processes including: evolution, cancer, and the development of the immune system, including junctional diversity. Mutati ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Holocarboxylase Synthetase Deficiency
Holocarboxylase synthetase deficiency is an inherited metabolic disorder in which the body is unable to use the vitamin biotin effectively. This disorder is classified as a multiple carboxylase deficiency, a group of disorders characterized by impaired activity of certain enzymes that depend on biotin. Symptoms are very similar to biotinidase deficiency and treatment – large doses of biotin – is also the same. Symptoms and signs Genetics Mutations in the ''HLCS'' gene cause holocarboxylase synthetase deficiency. The ''HLCS'' gene makes an enzyme, holocarboxylase synthetase, that attaches biotin to other molecules. Biotin, a B vitamin, is found in foods such as liver, egg yolks, and milk. It is essential for the normal production and breakdown of proteins, fats, and carbohydrates in the body. Mutations in the ''HLCS'' gene reduce the activity of holocarboxylase synthetase, preventing cells from using biotin effectively and disrupting many cellular functions. This condit ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Chromosome 21 (human)
Chromosome 21 is one of the 23 pairs of chromosomes in humans. Chromosome 21 is both the smallest human autosome and chromosome, with 46.7 million base pairs (the building material of DNA) representing about 1.5 percent of the total DNA in cells. Most people have two copies of chromosome 21, while those with three copies of chromosome 21 (trisomy 21) have Down syndrome. Researchers working on the Human Genome Project announced in May 2000 that they had determined the sequence of base pairs that make up this chromosome. Chromosome 21 was the second human chromosome to be fully sequenced, after chromosome 22. Genes Number of genes The following are some of the gene count estimates of human chromosome 21. Because researchers use different approaches to genome annotation, their predictions of the number of genes on each chromosome varies (for technical details, see gene prediction). Among various projects, the collaborative consensus coding sequence project ( CCDS) takes an ex ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Liver
The liver is a major metabolic organ (anatomy), organ exclusively found in vertebrates, which performs many essential biological Function (biology), functions such as detoxification of the organism, and the Protein biosynthesis, synthesis of various proteins and various other Biochemistry, biochemicals necessary for digestion and growth. In humans, it is located in the quadrants and regions of abdomen, right upper quadrant of the abdomen, below the thoracic diaphragm, diaphragm and mostly shielded by the lower right rib cage. Its other metabolic roles include carbohydrate metabolism, the production of a number of hormones, conversion and storage of nutrients such as glucose and glycogen, and the decomposition of red blood cells. Anatomical and medical terminology often use the prefix List of medical roots, suffixes and prefixes#H, ''hepat-'' from ἡπατο-, from the Greek language, Greek word for liver, such as hepatology, and hepatitis The liver is also an accessory digestive ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
