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Hepatic Fructokinase
Hepatic fructokinase (or ketohexokinase) is an enzyme that catalyzes the phosphorylation of fructose Fructose (), or fruit sugar, is a Ketose, ketonic monosaccharide, simple sugar found in many plants, where it is often bonded to glucose to form the disaccharide sucrose. It is one of the three dietary monosaccharides, along with glucose and gal ... to produce fructose-1-phosphate. :ATP + \longrightarrow ADP + : ATP + D-fructose → ADP + D-fructose-1-phosphate Pathology A deficiency is associated with essential fructosuria. References External links * EC 2.7.1 {{2.7-enzyme-stub ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Enzyme
An enzyme () is a protein that acts as a biological catalyst by accelerating chemical reactions. The molecules upon which enzymes may act are called substrate (chemistry), substrates, and the enzyme converts the substrates into different molecules known as product (chemistry), products. Almost all metabolism, metabolic processes in the cell (biology), cell need enzyme catalysis in order to occur at rates fast enough to sustain life. Metabolic pathways depend upon enzymes to catalyze individual steps. The study of enzymes is called ''enzymology'' and the field of pseudoenzyme, pseudoenzyme analysis recognizes that during evolution, some enzymes have lost the ability to carry out biological catalysis, which is often reflected in their amino acid sequences and unusual 'pseudocatalytic' properties. Enzymes are known to catalyze more than 5,000 biochemical reaction types. Other biocatalysts include Ribozyme, catalytic RNA molecules, also called ribozymes. They are sometimes descr ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Phosphorylation
In biochemistry, phosphorylation is described as the "transfer of a phosphate group" from a donor to an acceptor. A common phosphorylating agent (phosphate donor) is ATP and a common family of acceptor are alcohols: : This equation can be written in several ways that are nearly equivalent that describe the behaviors of various protonated states of ATP, ADP, and the phosphorylated product. As is clear from the equation, a phosphate group per se is not transferred, but a phosphoryl group (PO3-). Phosphoryl is an electrophile. This process and its inverse, dephosphorylation, are common in biology. Text was copied from this source, which is available under a Creative Commons Attribution 4.0 International License. Protein phosphorylation often activates (or deactivates) many enzymes. During respiration Phosphorylation is essential to the processes of both anaerobic and aerobic respiration, which involve the production of adenosine triphosphate (ATP), the "high-energy" exc ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Fructose
Fructose (), or fruit sugar, is a Ketose, ketonic monosaccharide, simple sugar found in many plants, where it is often bonded to glucose to form the disaccharide sucrose. It is one of the three dietary monosaccharides, along with glucose and galactose, that are absorbed by the gut directly into the blood of the portal vein during digestion. The liver then converts most fructose and galactose into glucose for distribution in the bloodstream or deposition into glycogen. Fructose was discovered by French chemist Augustin-Pierre Dubrunfaut in 1847. The name "fructose" was coined in 1857 by the English chemist William Allen Miller. Pure, dry fructose is a sweet, white, odorless, crystalline solid, and is the most water-soluble of all the sugars. Fructose is found in honey, tree and vine fruits, flowers, Berry, berries, and most List of root vegetables, root vegetables. Commercially, fructose is derived from sugar cane, sugar beets, and maize. High-fructose corn syrup is a mixture of ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Fructose-1-phosphate
Fructose-1-phosphate is a derivative of fructose. It is generated mainly by hepatic fructokinase but is also generated in smaller amounts in the small intestinal mucosa and proximal epithelium of the renal tubule. It is an important intermediate of glucose metabolism. Because fructokinase has a high Vmax fructose entering cells is quickly phosphorylated to fructose 1-phosphate."Marks A. Basic Medical Biochemistry: a clinical approach, 3rd ed. p.540 In this form it is usually accumulated in the liver until it undergoes further conversion by aldolase B (the rate limiting enzyme of fructose metabolism). Aldolase B converts it into glyceraldehyde and dihydroxyacetone phosphate (DHAP). Glyceraldehyde is then phosphorylated by triose kinase to glyceraldehyde 3-phosphate. Metabolism of fructose thus essentially results in intermediates of glycolysis. This means that fructose has the same fate as glucose after it gets metabolised. The final product of glycolysis (pyruvate) may then underg ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Adenosine Triphosphate
Adenosine triphosphate (ATP) is a nucleoside triphosphate that provides energy to drive and support many processes in living cell (biology), cells, such as muscle contraction, nerve impulse propagation, and chemical synthesis. Found in all known forms of life, it is often referred to as the "molecular unit of currency" for intracellular energy transfer. When consumed in a Metabolism, metabolic process, ATP converts either to adenosine diphosphate (ADP) or to adenosine monophosphate (AMP). Other processes regenerate ATP. It is also a Precursor (chemistry), precursor to DNA and RNA, and is used as a coenzyme. An average adult human processes around 50 kilograms (about 100 mole (unit), moles) daily. From the perspective of biochemistry, ATP is classified as a nucleoside triphosphate, which indicates that it consists of three components: a nitrogenous base (adenine), the sugar ribose, and the Polyphosphate, triphosphate. Structure ATP consists of three parts: a sugar, an amine base ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Adenosine Diphosphate
Adenosine diphosphate (ADP), also known as adenosine pyrophosphate (APP), is an important organic compound in metabolism and is essential to the flow of energy in living cells. ADP consists of three important structural components: a sugar backbone attached to adenine and two phosphate groups bonded to the 5 carbon atom of ribose. The diphosphate group of ADP is attached to the 5’ carbon of the sugar backbone, while the adenine attaches to the 1’ carbon. ADP can be interconverted to adenosine triphosphate (ATP) and adenosine monophosphate (AMP). ATP contains one more phosphate group than ADP, while AMP contains one fewer phosphate group. Energy transfer used by all living things is a result of dephosphorylation of ATP by enzymes known as ATPases. The cleavage of a phosphate group from ATP results in the coupling of energy to metabolic reactions and a by-product of ADP. ATP is continually reformed from lower-energy species ADP and AMP. The biosynthesis of ATP is achieved th ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Essential Fructosuria
Essential fructosuria, caused by a deficiency of the enzyme hepatic fructokinase, is a clinically benign condition characterized by the incomplete metabolism of fructose in the liver, leading to its excretion in urine. Fructokinase (sometimes called ketohexokinase) is the first enzyme involved in the degradation of fructose to fructose-1-phosphate in the liver. This defective degradation does not cause any clinical symptoms, fructose is either excreted unchanged in the urine or metabolized to fructose-6-phosphate by alternate pathways in the body, most commonly by hexokinase in adipose tissue and muscle. Signs and symptoms Cause Essential fructosuria is a genetic condition that is inherited in an autosomal recessive manner. Mutations in the ''KHK'' gene, located on chromosome 2p23.3-23.2 are responsible. The incidence of essential fructosuria has been estimated at 1:130,000. The actual incidence is likely higher, because those affected are asymptomatic. Diagnosis A diagnosis o ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
