Phospholipids, are a class of lipids whose molecule has a hydrophilic "head" containing a phosphate group and two hydrophobic "tails" derived from fatty acids, joined by an alcohol residue. Marine phospholipids typically have omega-3 fatty acids EPA and DHA integrated as part of the phospholipid molecule. The phosphate group can be modified with simple organic molecules such as choline, ethanolamine or serine.
Choline is an essential nutrient for humans and many other animals. Choline occurs as a cation that forms various salts. Humans are capable of some de novo synthesis of choline but require additional choline in the diet to maintain health. Dietary requirements can be met by choline per se or in the form of choline phospholipids, such as phosphatidylcholine. Choline is not formally classified as a vitamin despite being an essential nutrient with an amino acid–like structure and metabolism. In most animals, choline phospholipids are necessary components in cell membranes, in the membranes of cell organelles, and in very low-density lipoproteins. Choline is required to produce acetylcholine – a neurotransmitter – and S-adenosylmethionine (SAM), a universal methyl donor. Upon methylation SAM is transformed into homocysteine.
α-Amanitin (alpha-Amanitin) is a cyclic peptide of eight amino acids. It is possibly the most deadly of all the amatoxins, toxins found in several species of the mushroom genus Amanita, one being the death cap as well as the destroying angel, a complex of similar species, principally A. virosa and A. bisporigera. It is also found in the mushrooms Galerina marginata and Conocybe filaris. The oral LD50 of amanitin is 100 μg/kg for rats.
The rifamycins are a group of antibiotics that are synthesized either naturally by the bacterium Amycolatopsis rifamycinica or artificially. They are a subclass of the larger family of ansamycins. Rifamycins are particularly effective against mycobacteria, and are therefore used to treat tuberculosis, leprosy, and mycobacterium avium complex (MAC) infections.
RNA polymerase II is a multiprotein complex that transcribes DNA into precursors of messenger RNA (mRNA) and most small nuclear RNA (snRNA) and microRNA. It is one of the three RNAP enzymes found in the nucleus of eukaryotic cells. A 550 kDa complex of 12 subunits, RNAP II is the most studied type of RNA polymerase. A wide range of transcription factors are required for it to bind to upstream gene promoters and begin transcription.
The TATA-binding protein (TBP) is a general transcription factor that binds specifically to a DNA sequence called the TATA box. This DNA sequence is found about 30 base pairs upstream of the transcription start site in some eukaryotic gene promoters.
Topoisomerase inhibitors are chemical compounds that block the action of topoisomerases, which are broken into two broad subtypes: type I topoisomerases (TopI) and type II topoisomerases (TopII). Topoisomerase plays important roles in cellular reproduction and DNA organization, as they mediate the cleavage of single and double stranded DNA to relax supercoils, untangle catenanes, and condense chromosomes in eukaryotic cells. Topoisomerase inhibitors influence these essential cellular processes. Some topoisomerase inhibitors prevent topoisomerases from performing DNA strand breaks while others, deemed topoisomerase poisons, associate with topoisomerase-DNA complexes and prevent the re-ligation step of the topoisomerase mechanism. These topoisomerase-DNA-inhibitor complexes are cytotoxic agents, as the un-repaired single- and double stranded DNA breaks they cause can lead to apoptosis and cell death. Because of this ability to induce apoptosis, topoisomerase inhibitors have gained interest as therapeutics against infectious and cancerous cells.
Roger David Kornberg is an American biochemist and professor of structural biology at Stanford University School of Medicine. Kornberg was awarded the Nobel Prize in Chemistry in 2006 for his studies of the process by which genetic information from DNA is copied to RNA, "the molecular basis of eukaryotic transcription."
RNA-dependent RNA polymerase (RdRp) or RNA replicase is an enzyme that catalyzes the replication of RNA from an RNA template. Specifically, it catalyzes synthesis of the RNA strand complementary to a given RNA template. This is in contrast to typical DNA-dependent RNA polymerases, which all organisms use to catalyze the transcription of RNA from a DNA template.
Phospholipase A1 (EC 3.1.1.32; systematic name: phosphatidylcholine 1-acylhydrolase) encoded by the PLA1A gene is a phospholipase enzyme which removes the 1-acyl group:
DNA-directed RNA polymerase II subunit RPB1, also known as RPB1, is an enzyme that in humans is encoded by the POLR2A gene.
DNA-directed RNA polymerases I, II, and III subunit RPABC1 is a protein that in humans is encoded by the POLR2E gene.
DNA-directed RNA polymerase II subunit RPB7 is an enzyme that in humans is encoded by the POLR2G gene.
DNA-directed RNA polymerases I, II, and III subunit RPABC3 is a protein that in humans is encoded by the POLR2H gene.
Heterogeneous nuclear ribonucleoprotein U is a protein that in humans is encoded by the HNRNPU gene.
General transcription factor IIF subunit 2 is a protein that in humans is encoded by the GTF2F2 gene.
A protocell is a self-organized, endogenously ordered, spherical collection of lipids proposed as a stepping-stone toward the origin of life. A central question in evolution is how simple protocells first arose and how they could differ in reproductive output, thus enabling the accumulation of novel biological emergences over time, i.e. biological evolution. Although a functional protocell has not yet been achieved in a laboratory setting, the goal to understand the process appears well within reach.
Non-structural protein 5B (NS5B) inhibitors are a class of direct-acting antivirals widely used in the treatment of chronic hepatitis C. Depending on site of action and chemical composition, NS5B inhibitors may be categorized into three classes—nucleoside active site inhibitors (NIs), non-nucleoside allosteric inhibitors, and pyrophosphate analogues. Subsequently, all three classes are then subclassified. All inhibit RNA synthesis by NS5B but at different stages/sites resulting in inability of viral RNA replication. Expression of direct-acting NS5B inhibitors does not take place in cells that are not infected by hepatitis C virus, which seems to be beneficial for this class of drugs.
Fungal ribotoxins are a group of extracellular ribonucleases (RNases) secreted by fungi. Their most notable characteristic is their extraordinary specificity. They inactivate ribosomes by cutting a single phosphodiester bond of the rRNA that is found in a universally conserved sequence. This cleavage leads to cell death by apoptosis. However, since they are extracellular proteins, they must first enter the cells that constitute their target to exert their cytotoxic action. This entry constitutes the rate-determining step of their action.
Hordatine A is a phenolic secondary metabolite and an adrenergic antagonist that is found in barley. This natural product is a member of the class benzofurans, and can also be found in barley malt and beer, as it withstands moderate processing. Hordatine A is a hydroxycinnamic acid amide derivative (HCAA) as well as a dimer of coumaroyl agmatine, and is plentiful during the development of barley seedlings, specifically in the shoots. Hordatines and their hydroxycinnamoyl agmatine precursors are of interest because of their antifungal activity against plant pathogens, such as inhibiting spore germination of many fungi species. Hordatine A is thought to be a phytoanticipin, because it is observed in significant amounts in young seedlings and at early growth stages.
