Organic chemistry is a chemistry subdiscipline involving the scientific study of the structure, properties, and reactions of organic compounds and organic materials, i.e., matter in its various forms that contain carbon atoms. Study of structure includes using spectroscopy and other physical and chemical methods to determine the chemical composition and constitution of organic compounds and materials. Study of properties includes both physical properties and chemical properties, and uses similar methods as well as methods to evaluate chemical reactivity, with the aim to understand the behavior of the organic matter in its pure form (when possible), but also in solutions, mixtures, and fabricated forms. The study of organic reactions includes both their preparation—by synthesis or by other means—as well as their subsequent reactivities, both in the laboratory and via theoretical (in silico) study.
The range of chemicals studied in organic chemistry include hydrocarbons, compounds containing only carbon and hydrogen, as well as compositions based on carbon but containing other elements. Organic chemistry overlaps with many areas including medicinal chemistry, biochemistry, organometallic chemistry, and polymer chemistry, as well as many aspects of materials science.
An energy drink is a type of beverage containing stimulant drugs, chiefly caffeine, which is marketed as providing mental or physical stimulation. They may or may not be carbonated, and generally contain large amounts of caffeine and other stimulants, and many also contain sugar or other sweeteners, herbal extracts and amino acids. They are a subset of the larger group of energy products, which includes bars and gels. There are many brands and varieties of energy drinks.
Coffee, tea and other naturally caffeinated beverages are usually not considered energy drinks. Soft drinks such as cola, may contain caffeine, but are also not energy drinks. Some alcoholic beverages, such as Four Loko, contain caffeine and other stimulants and are marketed as energy drinks, although such drinks are banned in some American states.
A glucogenic amino acid is an amino acid that can be converted into glucose through gluconeogenesis. This is in contrast to the ketogenic amino acids, which are converted into ketone bodies.
The production of glucose from glucogenic amino acids involves these amino acids' being converted to alpha keto acids and then to glucose, with both processes occurring in the liver. This mechanism predominates during catabolysis, rising as fasting and starvation increase in severity.
Proteinogenic amino acids are amino acids that are precursors to proteins, and are produced by cellular machinery coded for in the genetic code of any organism. There are 22 standard amino acids, but only 21 are found in eukaryotes. Of the 22, selenocysteine and pyrrolysine are incorporated into proteins by distinctive biosynthetic mechanisms. The other 20 are directly encoded by the universal genetic code. Humans can synthesize 11 of these 20 from each other or from other molecules of intermediary metabolism. The other 9 must be consumed (usually as their protein derivatives) in the diet and so are thus called essential amino acids. The essential amino acids are histidine, isoleucine, leucine, lysine, methionine, phenylalanine, threonine, tryptophan, and valine.
The word proteinogenic means "protein building". Proteinogenic amino acids can be condensed into a polypeptide (the subunit of a protein) through a process called translation (the second stage of protein biosynthesis, part of the overall process of gene expression).
Amino acids (//, //, or //) are biologically important organic compounds composed of amine (-NH2) and carboxylic acid (-COOH) functional groups, along with a side-chain specific to each amino acid. The key elements of an amino acid are carbon, hydrogen, oxygen, and nitrogen, though other elements are found in the side-chains of certain amino acids. About 500 amino acids are known and can be classified in many ways. Structurally they can be classified according to the functional groups' locations as alpha- (α-), beta- (β-), gamma- (γ-) or delta- (δ-) amino acids; other categories relate to polarity, pH level, and side chain group type (aliphatic, acyclic, aromatic, containing hydroxyl or sulfur, etc.) In the form of proteins, amino acids comprise the second largest component (after water) of human muscles, cells and other tissues. Outside proteins, amino acids perform critical roles in processes such as neurotransmitter transport and biosynthesis.
Amino acids having both the amine and carboxylic acid groups attached to the first (alpha-) carbon atom have particular importance in biochemistry. They are known as 2-, alpha-, or α-amino acids (generic formula H2NCHRCOOH in most cases where R is an organic substituent known as a "side-chain"); often the term "amino acid" is used to refer specifically to these. They include the 22 proteinogenic ("protein-building") amino acids which combine into peptide chains ("polypeptides") to form the building blocks of a vast array of proteins. These are all L-stereoisomers ("left-handed" isomers) although a few D-amino acids ("right-handed") occur in bacterial envelopes and some antibiotics. Twenty of the proteinogenic amino acids are encoded directly by triplet codons in the genetic code and are known as "standard" amino acids. The other two ("non-standard" or "non-canonical") are pyrrolysine (found in methanogenic organisms and other eukaryotes) and selenocysteine (present in many noneukaryotes as well as most eukaryotes). For example, 25 human proteins include selenocysteine (Sec) in their primary structure, and the structurally characterized enzymes (selenoenzymes) employ Sec as the catalytic moiety in their active sites. Pyrrolysine and selenocysteine are encoded via variant codons; for example, selenocysteine is encoded by stop codon and SECIS element. Codon–tRNA combinations not found in nature can also be used to "expand" the genetic code and create novel proteins known as alloproteins incorporating non-proteinogenic amino acids.
Cysteine dioxygenase (CDO, CAS number: 37256-59-0) is a mammalian non-heme iron enzyme that catalyzes the conversion of L-cysteine to cysteine sulfinic acid (cysteine sulfinate) by incorporation of dioxygen.
Cysteine sulfinic acid lies at a branch-point in cysteine catabolism, where it can follow two pathways resulting in the formation of taurine or sulfate. The cysteine sulfinic acid-dependent pathway of taurine metabolism follows the synthesis of hypotaurine (2-aminoethane sulfinate), which is subsequently oxidized to taurine. Also, cysteine sulfinate can undergo transamination to form β-sulfinylpyruvate, decomposing to form pyruvate and sulfite.