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β-oxidation
In biochemistry and metabolism, beta oxidation (also β-oxidation) is the catabolic process by which fatty acid molecules are broken down in the cytosol in prokaryotes and in the mitochondria in eukaryotes to generate acetyl-CoA. Acetyl-CoA enters the citric acid cycle, generating NADH and FADH2, which are electron carriers used in the electron transport chain. It is named as such because the beta carbon of the fatty acid chain undergoes oxidation and is converted to a carbonyl group to start the cycle all over again. Beta-oxidation is primarily facilitated by the mitochondrial trifunctional protein, an enzyme complex associated with the inner mitochondrial membrane, although very long chain fatty acids are oxidized in peroxisomes. The overall reaction for one cycle of beta oxidation is: :C''n''-acyl-CoA + FAD + NAD''+'' + H''2''O + CoA → C''n''-2-acyl-CoA + FADH''2'' + NADH + H''+'' + acetyl-CoA Activation and membrane transport Free fatty acids cannot penetrate any biologi ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Acetyl-CoA
Acetyl-CoA (acetyl coenzyme A) is a molecule that participates in many biochemical reactions in protein, carbohydrate and lipid metabolism. Its main function is to deliver the acetyl group to the citric acid cycle (Krebs cycle) to be oxidation, oxidized for energy production. Coenzyme A (CoASH or CoA) consists of a cysteamine, β-mercaptoethylamine group linked to pantothenic acid (vitamin B5) through an amide linkage and 3'-phosphorylated ADP. The acetyl group (indicated in blue in the structural diagram on the right) of acetyl-CoA is linked to the sulfhydryl substituent of the β-mercaptoethylamine group. This thioester linkage is a "high energy" bond, which is particularly reactive. Hydrolysis of the thioester bond is exergonic (−31.5 kJ/mol). CoA is acetylated to acetyl-CoA by the breakdown of carbohydrates through glycolysis and by the breakdown of fatty acids through Beta oxidation, β-oxidation. Acetyl-CoA then enters the citric acid cycle, where the acetyl group is ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Peroxisome
A peroxisome () is a membrane-bound organelle, a type of microbody, found in the cytoplasm of virtually all eukaryotic cells. Peroxisomes are oxidative organelles. Frequently, molecular oxygen serves as a co-substrate, from which hydrogen peroxide (H2O2) is then formed. Peroxisomes owe their name to hydrogen peroxide-generating and scavenging activities. They perform key roles in lipid metabolism and the redox, reduction of reactive oxygen species. Peroxisomes are involved in the catabolism of very long chain fatty acids, branched chain fatty acids, bile acid intermediates (in the liver), D-amino acids, and polyamines. Peroxisomes also play a role in the biosynthesis of plasmalogens: ether phospholipids critical for the normal function of mammalian brains and lungs. Peroxisomes contain approximately 10% of the total activity of two enzymes (Glucose-6-phosphate dehydrogenase and Phosphogluconate dehydrogenase, 6-Phosphogluconate dehydrogenase) in the pentose phosphate pathway, ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Carnitine
Carnitine is a quaternary ammonium compound involved in metabolism in most mammals, plants, and some bacteria. In support of energy metabolism, carnitine transports long-chain fatty acids from the cytosol into mitochondria to be oxidized for free energy production, and also participates in removing products of metabolism from cells. Given its key metabolic roles, carnitine is concentrated in tissues like skeletal and cardiac muscle that metabolize fatty acids as an energy source. Generally individuals, including strict vegetarians, synthesize enough L-carnitine in vivo. Carnitine exists as one of two stereoisomers: the two enantiomers -carnitine (''S''-(+)-) and -carnitine (''R''-(−)-). Both are biologically active, but only -carnitine naturally occurs in animals, and -carnitine is toxic as it inhibits the activity of the -form. At room temperature, pure carnitine is a whiteish powder, and a water-soluble zwitterion with relatively low toxicity. Derived from amino acids, ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Long-chain-fatty-acid—CoA Ligase
The long chain fatty acyl-CoA ligase (or synthetase) is an enzyme () of the ligase family that activates the oxidation of complex fatty acids. Long chain fatty acyl-CoA synthetase catalyzes the formation of fatty acyl-CoA by a two-step process proceeding through an adenylation, adenylated intermediate. The enzyme catalyzes the following reaction, :Fatty acid + coenzyme A, CoA + adenosine triphosphate, ATP ⇌ Acyl-CoA + adenosine monophosphate, AMP + pyrophosphate, PPi It is present in all organisms from bacteria to humans. It catalyzes the pre-step reaction for β-oxidation of fatty acids or can be incorporated in phospholipids. Function Long chain fatty acyl-CoA synthetase, LC-FACS, plays a role in the physiological regulation of various cellular functions via the production of long chain fatty acyl-CoA esters, which reportedly have affected protein transport, enzyme activation, protein acylation, cell signaling, and transcriptional regulation. The formation of fatty acyl-Co ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Transport Proteins
A transport protein (variously referred to as a transmembrane pump, transporter, escort protein, acid transport protein, cation transport protein, or anion transport protein) is a protein that serves the function of moving other materials within an organism. Transport proteins are vital to the growth and life of all living things. There are several different kinds of transport proteins. Carrier proteins are proteins involved in the movement of ions, small molecules, or macromolecules, such as another protein, across a biological membrane. Carrier proteins are integral membrane proteins; that is, they exist within and span the membrane across which they transport substances. The proteins may assist in the movement of substances by facilitated diffusion (i.e., passive transport) or active transport. These mechanisms of movement are known as carrier-mediated transport. Each carrier protein is designed to recognize only one substance or one group of very similar substances. R ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Short-chain Fatty Acid
Short-chain fatty acids (SCFAs) are fatty acids of two to six carbon atoms. The SCFAs' lower limit is interpreted differently, either with one, two, three or four carbon atoms. Derived from intestine, intestinal microbe, microbial fermentation of indigestible foods, SCFAs in human gut are acetic, propionic and butyric acid. They are the main energy source of colonocytes, making them crucial to gastrointestinal health. SCFAs all possess varying degrees of water solubility, which distinguishes them from longer chain fatty acids that are immiscible. List of SCFAs Functions SCFAs are produced when dietary fiber is fermented in the Colon (anatomy), colon. Macronutrient composition (carbohydrate, protein or fat) of diets affects circulating SCFAs. Acetate, propionate and butyrate are the three most common SCFAs. Butyric acid, Butyrate is particularly important for large intestine, colon health because it is the primary energy source for Gastrointestinal tract#Mucosa, colonocytes (the ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Carnitine Palmitoyltransferase II
Carnitine O-palmitoyltransferase 2, mitochondrial is an enzyme that in humans is encoded by the ''CPT2'' gene In biology, the word gene has two meanings. The Mendelian gene is a basic unit of heredity. The molecular gene is a sequence of nucleotides in DNA that is transcribed to produce a functional RNA. There are two types of molecular genes: protei .... Function Carnitine palmitoyltransferase II precursor (CPT2) is a mitochondrial membrane protein which is transported to the mitochondrial inner membrane. CPT2 together with carnitine palmitoyltransferase I oxidizes long-chain fatty acids in the mitochondria. Defects in this gene are associated with mitochondrial long-chain fatty-acid (LCFA) oxidation disorders and carnitine palmitoyltransferase II deficiency. See also * Carnitine palmitoyltransferase I References Further reading * * * * * * * * * * * * * * * * * * * {{Mitochondrial enzymes Human proteins ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Carnitine-acylcarnitine Translocase
Carnitine-acylcarnitine translocase (CACT) is responsible for passive transport of carnitine and carnitine-fatty acid complexes and across the inner mitochondrial membrane as part of the carnitine shuttle system. Function Fatty acyl–carnitine can diffuse from the cytosol across the porous outer mitochondrial membrane to the intermembrane space, but must utilize CACT to cross the nonporous inner mitochondrial membrane and reach the mitochondrial matrix. CACT is a cotransporter, returning one molecule of carnitine from the matrix to the intermembrane space The intermembrane space (IMS) is the space occurring between or involving two or more membranes. In cell biology, it is most commonly described as the region between the Inner mitochondrial membrane, inner membrane and the Outer mitochondrial memb ... as one molecule of fatty acyl–carnitine moves into the matrix. Clinical significance A disorder is associated with carnitine-acylcarnitine translocase deficiency. This dis ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Inner Mitochondrial Membrane
The inner mitochondrial membrane (IMM) is the mitochondrial membrane which separates the mitochondrial matrix from the intermembrane space. Structure The structure of the inner mitochondrial membrane is extensively folded and compartmentalized. The numerous invaginations of the membrane are called cristae, separated by crista junctions from the inner boundary membrane juxtaposed to the outer membrane. Cristae significantly increase the total membrane surface area compared to a smooth inner membrane and thereby the available working space for oxidative phosphorylation. The inner membrane creates two compartments. The region between the inner and outer membrane, called the intermembrane space, is largely continuous with the cytosol, while the more sequestered space inside the inner membrane is called the matrix. Cristae For typical liver mitochondria, the area of the inner membrane is about 5 times as large as the outer membrane due to cristae. This ratio is variable and mitocho ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Outer Mitochondrial Membrane
A mitochondrion () is an organelle found in the cells of most eukaryotes, such as animals, plants and fungi. Mitochondria have a double membrane structure and use aerobic respiration to generate adenosine triphosphate (ATP), which is used throughout the cell as a source of chemical energy. They were discovered by Albert von Kölliker in 1857 in the voluntary muscles of insects. The term ''mitochondrion'', meaning a thread-like granule, was coined by Carl Benda in 1898. The mitochondrion is popularly nicknamed the "powerhouse of the cell", a phrase popularized by Philip Siekevitz in a 1957 ''Scientific American'' article of the same name. Some cells in some multicellular organisms lack mitochondria (for example, mature mammalian red blood cells). The multicellular animal '' Henneguya salminicola'' is known to have retained mitochondrion-related organelles despite a complete loss of their mitochondrial genome. A large number of unicellular organisms, such as microsporidia, ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Carnitine Palmitoyltransferase I
Carnitine palmitoyltransferase I (CPT1) also known as carnitine acyltransferase I, CPTI, CAT1, CoA:carnitine acyl transferase (CCAT), or palmitoylCoA transferase I, is a mitochondrial enzyme responsible for the formation of acyl carnitines by catalyzing the transfer of the acyl group of a long-chain fatty acyl-CoA from coenzyme A to l-carnitine. The product is often palmitoylcarnitine (thus the name), but other fatty acids may also be substrates. It is part of a family of enzymes called carnitine acyltransferases. This "preparation" allows for subsequent movement of the acyl carnitine from the cytosol into the intermembrane space of mitochondria. Three isoforms of CPT1 are currently known: CPT1A, CPT1B, and CPT1C. CPT1 is associated with the outer mitochondrial membrane. This enzyme can be inhibited by malonyl CoA, the first committed intermediate produced during fatty acid synthesis. Its role in fatty acid metabolism makes CPT1 important in many metabolic disorders s ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Adenosine Monophosphate
Adenosine monophosphate (AMP), also known as 5'-adenylic acid, is a nucleotide. AMP consists of a phosphate group, the sugar ribose, and the nucleobase adenine. It is an ester of phosphoric acid and the nucleoside adenosine. As a substituent it takes the form of the prefix adenylyl-. AMP plays an important role in many cellular metabolic processes, being interconverted to adenosine triphosphate (ATP) and adenosine diphosphate (ADP), as well as allosterically activating enzymes such as myophosphorylase-b. AMP is also a component in the synthesis of RNA. AMP is present in all known forms of life. Production and degradation AMP does not have the high energy phosphoanhydride bond associated with ADP and ATP. AMP can be produced from ADP by the myokinase (adenylate kinase) reaction when the ATP reservoir in the cell is low: : 2 ADP → ATP + AMP Or AMP may be produced by the hydrolysis of one high energy phosphate bond of ADP: : ADP + H2O → AMP + Pi AMP can also be forme ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
