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Polyketides are a class of natural products produced by bacteria, fungi, and plants through biosynthesis from acetyl-CoA and malonyl-CoA building blocks. They have a diverse range of biological activities, including antibiotic, antifungal, antiparasitic, and anticancer properties. Many important drugs, such as erythromycin and lovastatin, are derived from polyketides.
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What has the author Curtis Lee Kirkemo written?
Curtis Lee Kirkemo has written: 'Approaches to the synthesis of polyketides. Vermiculine' -- subject(s): Polyketides
What has the author Seong-tshool Hong written?
Seong-tshool Hong has written: 'Cloning and characterization of polyketide biosynthetic gene clusters from Streptomyces murayamaensis, Streptomyces rimosus, and Streptomyces WP 4669' -- subject(s): Genetic aspects, Genetic aspects of Polyketides, Genetics, Polyketides, Streptomyces
What is a callystatin?
A callystatin is any of a class of cytotoxic polyketides, found in marine sponges of the genus Callyspongia, which have antibiotic activity.
What has the author David O'Hagan written?
David O'Hagan has written: 'The polyketide metabolites' -- subject(s): Metabolism, Natural products, Polyketides, Synthesis
What is the pharmacological function of tannins?
Tannins are phenolic compounds found in many plant species. Tannins deter against animal consumption due to a bitter taste and/or toxic consequences upon injestion. Phenolics is a category secondary metabolites. Other categories of secondary metabolites include Alkaloids, Terpenoids and Polyketides. Penolics are antioxidants with intense flavors and smells.
What are 4 types of lipids?
There could be many ways to classify libids. the first classification is the following : 1- saturated fats 2- monounsaturated fats 3- polyunsaturated fats 4- cholesterol 5- hydrogenated oils The second classification is the following : 1- acyls 2- glycerolipids 3- glycerophospholipids 4- sphingolibids 5- sterol 6- prenol 7- saccharolibids 8- polyketides The thirds classification is the following : 1- triglycerides 2- fatty acids 3- waxes 4- steriods 5- terpenes and many more... The fourth classification is the following : 1- triglyceride 2- cholesterol 3- phospholipids 4- fatty acids The fifth classification is for the liboproteins : 1- chelomicrons 2- LDL 3- VLDL 4- HDL
What are two groups of lipid?
There are four main groups of lipids. They are fatty acids, glycerides, non glycerides, and complex lipids. The groups are determined based on storage of energy, structure of cell membranes, and signal of chemical biological activities.
What is the definition of lipid fats?
Lipids are a broad group of naturally occurring molecules which includes fats, waxes, sterols, fat-soluble vitamins (such as vitamins A, D, E and K), monoglycerides, diglycerides, phospholipids, and others. The main biological functions of lipids include energy storage, as structural components of cell membranes, and as important signaling molecules.Lipids may be broadly defined as hydrophobic or amphiphilic small molecules; the amphiphilic nature of some lipids allows them to form structures such as vesicles, liposomes, or membranes in an aqueous environment. Biological lipids originate entirely or in part from two distinct types of biochemical subunits or "building blocks": ketoacyl and isoprene groups.Using this approach, lipids may be divided into eight categories: fatty acyls, glycerolipids, glycerophospholipids, sphingolipids, saccharolipids and polyketides (derived from condensation of ketoacyl subunits); and sterol lipids and prenol lipids (derived from condensation of isoprene subunits).Although the term lipid is sometimes used as a synonym for fats, fats are a subgroup of lipids called triglycerides. Lipids also encompass molecules such as fatty acids and their derivatives (including tri-, di-, and monoglycerides and phospholipids), as well as other sterol-containing metabolites such as cholesterol. Although humans and other mammals use various biosynthetic pathways to both break down and synthesize lipids, some essential lipids cannot be made this way and must be obtained from the diet.
What are six types of lipids?
Dietary Forms with Type Description1-Fatty AcidHydrocarbon chain with carboxylic acid2-Saturated· Has maximum number of hydrogens on the carbon chain· Solid at room temperature· High melting point· Found in meats, poultry, and dairy foods; coconut and palm oils3-Trans· Product of hydrogenation which increases the saturation of fatty acids within oils and converts natural cis to trans configuration· Consist of straighter chains than natural unsaturated fatty acids· Industrial process that chemically transforms a low melting point oil into a solid fat with a higher melting point to enhance product taste, stability and shelf life.· Found in commercially fried foods, commercial baked goods and snacks, margarine, and vegetable shortenings4-Monounsaturated· Contain one double bond· Liquid at room temperature.· Found in olive, peanut and canola oils; nuts, avocados, and olives.5-Polyunsaturated· Contain two or more double bonds· Liquid at room temperature.· Found in corn, soybean, safflower and sunflower seed oils, and fish.· w (omega) 3 FATTY ACIDS:1) Linolenic acid (18:3w3)2) Eicosapentaenoic acid (20:5w3)3) Docosahexaenoic acid (22:6w3)· w (omega) 6 FATTY ACIDS1) Linoleic acid (18:2w6)2) Arachidonic fatty acid (20:4w6)· ESSENTIAL FATTY ACIDS (must be obtained from the diet)1) Linoleic acid (18:2w6)2) Linolenic acid (18:3w3)6-Triglycerides· Neutral esters of glycerol and fatty acids· Most contain different types of fatty acids (mixed)· Most common form of dietary fats and oils
What is the job of a lipid in the body?
The three major purposes of lipids are energy storage, cell membrane development, and serving as a component to hormones and vitamins in the body. In healthcare, physicians order lipid tests or lipid profiles to measure cholesterol and triglycerides in a person's blood. Lipoprotein is the medical term used to define a combination of fat and protein.Cholesterol is a naturally occurring substance in the body and is comprised of lipids. Cholesterol is separated into two types, high-density lipoprotein (HDL) and low-density lipoprotein (LDL). In a lipid test, the lipoproteins are separated so the level of each can be measured. Lipid tests are often part of preventative routine care, as they help determine whether there is significant risk for artherosclerosis, a hardening of the arteries that interferes with or interrupts blood flow. Lipoprotein levels are measured and dietary changes are usually in order when total cholesterol levels approach or rise above 200 milligrams per deciliter in the blood.Fatty Acids, also comprised of lipids, are an important dietary concern. Some fatty acids are essential and others are harmful. Fatty acids are categorized as mono-saturated, mono-unsaturated and poly-unsaturated.
What are 4 types of lipids and their function?
Fatty acylsFatty acyls, a generic term for describing fatty acids, their conjugates and derivatives, are a diverse group of molecules synthesized by chain-elongation of an acetyl-CoA primer with malonyl-CoA or methylmalonyl-CoA groups in a process called fatty acid synthesis. They are made of a hydrocarbon chain that terminates with a carboxylic acid group; this arrangement confers the molecule with a polar, hydrophilic end, and a nonpolar, hydrophobic end that is insoluble in water. The fatty acid structure is one of the most fundamental categories of biological lipids, and is commonly used as a building block of more structurally complex lipids. The carbon chain, typically between four to 24 carbons long, may be saturated or unsaturated, and may be attached to functional groups containing oxygen, halogens, nitrogen and sulfur. Where a double bond exists, there is the possibility of either a ''cis'' or ''trans'' geometric isomerism, which significantly affects the molecule's molecular configuration. ''Cis''-double bonds cause the fatty acid chain to bend, an effect that is more pronounced the more double bonds there are in a chain. This in turn plays an important role in the structure and function of cell membranes. Most naturally occurring fatty acids are of the ''cis'' configuration, although the ''trans'' form does exist in some natural and partially hydrogenated fats and oils. Examples of biologically important fatty acids are the eicosanoids, derived primarily from arachidonic acid and eicosapentaenoic acid, which include prostaglandins, leukotrienes, and thromboxanes. Other major lipid classes in the fatty acid category are the fatty esters and fatty amides. Fatty esters include important biochemical intermediates such as wax esters, fatty acid thioester coenzyme A derivatives, fatty acid thioester ACP derivatives and fatty acid carnitines. The fatty amides include N-acyl ethanolamines, such as the cannabinoid neurotransmitter anandamide.Glycerolipids (triglycerides)Glycerolipids are composed mainly of mono-, di- and tri-substituted glycerols, the most well-known being the fatty acid esters of glycerol (triacylglycerols), also known as triglycerides. In these compounds, the three hydroxyl groups of glycerol are each esterified, usually by different fatty acids. Because they function as a food store, these lipids comprise the bulk of storage fat in animal tissues. The hydrolysis of the ester bonds of triacylglycerols and the release of glycerol and fatty acids from adipose tissue is called fat mobilization. Additional subclasses of glycerolipids are represented by glycosylglycerols, which are characterized by the presence of one or more sugar residues attached to glycerol via a glycosidic linkage. Examples of structures in this category are the digalactosyldiacylglycerols found in plant membranes and seminolipid from mammaliansperm cells.GlycerophospholipidsGlycerophospholipids, also referred to as phospholipids, are ubiquitous in nature and are key components of the lipid bilayer of cells, as well as being involved in metabolismand cell signaling. Neural tissue (including the brain) contains relatively high amounts of glycerophospholipids, and alterations in their composition has been implicated in various neurological disorders. Glycerophospholipids may be subdivided into distinct classes, based on the nature of the polar headgroup at the ''sn''-3 position of the glycerol backbone in eukaryotes and eubacteria, or the ''sn''-1 position in the case of archaebacteria.Examples of glycerophospholipids found in biological membranes are phosphatidylcholine (also known as PC, GPCho or lecithin), phosphatidylethanolamine (PE or GPEtn) and phosphatidylserine (PS or GPSer). In addition to serving as a primary component of cellular membranes and binding sites for intra- and intercellular proteins, some glycerophospholipids in eukaryotic cells, such as phosphatidylinositols and phosphatidic acids are either precursors of, or are themselves, membrane-derived second messengers. Typically, one or both of these hydroxyl groups are acylated with long-chain fatty acids, but there are also alkyl-linked and 1Z-alkenyl-linked (plasmalogen) glycerophospholipids, as well as dialkylether variants in archaebacteria. SphingolipidsSphingolipids are a complex family of compounds that share a common structural feature, a sphingoid base backbone that is synthesized ''de novo'' from the amino acid serine and a long-chain fatty acyl CoA, then converted into ceramides, phosphosphingolipids, glycosphingolipids and other compounds. The major sphingoid base of mammals is commonly referred to as sphingosine. Ceramides (N-acyl-sphingoid bases) are a major subclass of sphingoid base derivatives with an amide-linked fatty acid. The fatty acids are typically saturated or mono-unsaturated with chain lengths from 16 to 26 carbon atoms.The major phosphosphingolipids of mammals are sphingomyelins (ceramide phosphocholines), whereas insects contain mainly ceramide phosphoethanolamines and fungi have phytoceramide phosphoinositols and mannose-containing headgroups. The glycosphingolipids are a diverse family of molecules composed of one or more sugar residues linked via a glycosidic bond to the sphingoid base. Examples of these are the simple and complex glycosphingolipids such as cerebrosides and gangliosides. Sterol lipidsSterol lipids, such as cholesterol and its derivatives, are an important component of membrane lipids, along with the glycerophospholipids and sphingomyelins. The steroids, all derived from the same fused four-ring core structure, have different biological roles as hormones and signaling molecules. The eighteen-carbon (C18) steroids include theestrogen family whereas the C19 steroids comprise the androgens such astestosterone and androsterone. The C21 subclass includes the progestogens as well as the glucocorticoids and mineralocorticoids. The secosteroids, comprising various forms of vitamin D, are characterized by cleavage of the B ring of the core structure. Other examples of sterols are the bile acids and their conjugates, which in mammals are oxidized derivatives of cholesterol and are synthesized in the liver. The plant equivalents are the phytosterols, such as β-sitosterol, stigmasterol, and brassicasterol; the latter compound is also used as a biomarker for algal growth. The predominant sterol in fungal cell membranes is ergosterol. Prenol lipidsPrenol lipids are synthesized from the 5-carbon precursors isopentenyl diphosphate and dimethylallyl diphosphate that are produced mainly via the mevalonic acid (MVA) pathway. The simple isoprenoids (linear alcohols, diphosphates, etc.) are formed by the successive addition of C5 units, and are classified according to number of these terpene units. Structures containing greater than 40 carbons are known as polyterpenes. Carotenoids are important simple isoprenoids that function as antioxidants and as precursors of vitamin A. Another biologically important class of molecules is exemplified by the quinones and hydroquinones, which contain an isoprenoid tail attached to a quinonoid core of non-isoprenoid origin. Vitamin E andvitamin K, as well as the ubiquinones, are examples of this class. Prokaryotes synthesize polyprenols (called bactoprenols) in which the terminal isoprenoid unit attached to oxygen remains unsaturated, whereas in animal polyprenols (dolichols) the terminal isoprenoid is reduced. SaccharolipidsSaccharolipids describe compounds in which fatty acids are linked directly to a sugar backbone, forming structures that are compatible with membrane bilayers. In the saccharolipids, a monosaccharide substitutes for the glycerol backbone present in glycerolipids and glycerophospholipids. The most familiar saccharolipids are the acylated glucosamine precursors of the Lipid A component of the lipopolysaccharides in Gram-negative bacteria. Typical lipid A molecules are disaccharides of glucosamine, which are derivatized with as many as seven fatty-acyl chains. The minimal lipopolysaccharide required for growth in ''E. coli'' is Kdo2-Lipid A, a hexa-acylated disaccharide of glucosamine that is glycosylated with two 3-deoxy-D-manno-octulosonic acid (Kdo) residues. PolyketidesPolyketides are synthesized by polymerization of acetyl and propionyl subunits by classic enzymes as well as iterative and multimodular enzymes that share mechanistic features with the fatty acid synthases. They comprise a large number of secondarymetabolites and natural products from animal, plant, bacterial, fungal and marine sources, and have great structural diversity. Many polyketides are cyclic molecules whose backbones are often further modified by glycosylation, methylation, hydroxylation, oxidation, and/or other processes. Many commonly used anti-microbial, anti-parasitic, and anti-cancer agents are polyketides or polyketide derivatives, such as erythromycins, tetracyclines, avermectins, and antitumor epothilones.
