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Mannosidosis
Mannosidosis is a deficiency in mannosidase, an enzyme. There are two types: * Alpha-mannosidosis * Beta-mannosidosis See also *Swainsonine Swainsonine is an indolizidine alkaloid. It is a potent inhibitor of Golgi alpha-mannosidase II, an immunomodulator, and a potential chemotherapy drug. As a toxin in locoweed (likely its primary toxin) it also is a significant cause of economi ... References {{Glycoproteinoses Glycoprotein metabolism disorders ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Alpha-mannosidosis
Alpha-mannosidosis is a lysosomal storage disorder, first described by Swedish physician Okerman in 1967.''Malm D, Nilssen O (2008). "Alpha-mannosidosis". Orphanet J Rare Dis. 3 (1): 21. doi:10.1186/1750-1172-3-21. PMC 2515294 . PMID 18651971'' In humans it is known to be caused by an autosomal recessive genetic mutation in the gene MAN2B1, located on chromosome 19, affecting the production of the enzyme alpha-D-mannosidase, resulting in its deficiency.''Alpha-Mannosidosis Mutation Database. Tromsoe University. Available at'' Consequently, if both parents are carriers, there will be a 25% chance with each pregnancy that the defective gene from both parents will be inherited, and the child will develop the disease. There is a two in three chance that unaffected siblings will be carriers (Figure 1). In livestock alpha-mannosidosis is caused by chronic poisoning with swainsonine from locoweed. Symptoms Alpha-mannosidosis is a lifelong multi-systemic progressive disease, with n ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Beta-mannosidosis
Beta-mannosidosis, also called lysosomal beta-mannosidase deficiency, is a disorder of oligosaccharide metabolism caused by decreased activity of the enzyme beta-mannosidase. This enzyme is coded for by the gene '' MANBA'', located at 4q22-25. Beta-mannosidosis is inherited in an autosomal recessive manner. Affected individuals appear normal at birth, and can have a variable clinical presentation. Infantile onset forms show severe neurodegeneration, while some children have intellectual disability. Hearing loss and angiokeratomas are common features of the disease. Symptoms and signs The initial affected individual described in 1986 had a complex phenotype, and was later found to have both beta-mannosidosis and Sanfilippo syndrome. People have been described with a wide spectrum of clinical presentations from infants and children with intellectual disability to adults who present with isolated skin findings (angiokeratomas). Most cases are identified in the first year of lif ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Swainsonine
Swainsonine is an indolizidine alkaloid. It is a potent inhibitor of Golgi alpha-mannosidase II, an immunomodulator, and a potential chemotherapy drug. As a toxin in locoweed (likely its primary toxin) it also is a significant cause of economic losses in livestock industries, particularly in North America. It was first isolated from '' Swainsona canescens''. Pharmacology Swainsonine inhibits glycoside hydrolases, specifically N-linked glycosylation. Disruption of Golgi alpha-mannosidase II with swainsonine induces hybrid-type glycans. These glycans have a Man5GlcNAc2 core with processing on the 3-arm that resembles so-called complex-type glycans. The pharmacological properties of this product have not been fully investigated. Sources Some plants do not produce the toxic compound itself; they are host of endophytic fungi which produces swainsonine. Biosynthesis The biosynthesis of swainsonine has been investigated in the fungus ''Rhizoctonia leguminicola'', and it ini ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Mannosidase
Mannosidase is an enzyme which hydrolyses mannose. There are two types: * alpha-Mannosidase * beta-Mannosidase Beta-mannosidase (, ''mannanase'', ''mannase'', ''beta-D-mannosidase'', ''beta-mannoside mannohydrolase'', ''exo-beta-D-mannanase'', ''lysosomal beta A mannosidase'') is an enzyme with List of enzymes, systematic name ''beta-D-mannoside mannoh ... A deficiency is associated with mannosidosis. A family of mannosidases are also responsible for processing newly formed glycoproteins in the endoplasmic reticulum into mature glycoproteins containing highly heterogeneous complex-type glycans. References EC 3.2.1 {{3.2-enzyme-stub ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Enzyme
Enzymes () are proteins that act as biological catalysts by accelerating chemical reactions. The molecules upon which enzymes may act are called substrates, and the enzyme converts the substrates into different molecules known as products. Almost all metabolic processes in the 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 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 are catalytic RNA molecules, called ribozymes. Enzymes' specificity comes from their unique three-dimensional structures. Like all catalysts, enzymes increase the reaction ra ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
