In enzymology, a cyclomaltodextrin glucanotransferase (also cyclodextrin glycosyl transferase or CGTase for short) (EC2.4.1.19) is an enzyme that catalyzes the chemical reaction of cyclizing part of a 1,4-alpha-D-glucan molecule through the formation of a 1,4-alpha-D-glucosidic bond. They are bacterialenzymes belonging to the same family of the α-amylase specifically known as glycosyl-hydrolase family 13. This peculiar enzyme is capable of catalyzing more than one reaction with the most important being the synthesis of non-reducing cyclic dextrins known as cyclodextrins starting from starch, amylose, and other polysaccharides.
CGTase is an enzyme common to many bacterial species, in particular of the Bacillusgenus (e.g. B. circulans, B. macerans and B. stearothermophilus) and Brevibacillus brevis.
This enzyme belongs to the family of glycosyltransferases, specifically the hexosyltransferases. The systematic name of this enzyme class is 1,4-alpha-D-glucan 4-alpha-D-(1,4-alpha-D-glucano)-transferase (cyclizing). Other names in common use include Bacillus macerans amylase, cyclodextrin glucanotransferase, alpha-cyclodextrin glucanotransferase, alpha-cyclodextrin glycosyltransferase, beta-cyclodextrin glucanotransferase, beta-cyclodextrin glycosyltransferase, gamma-cyclodextrin glycosyltransferase, cyclodextrin glycosyltransferase, cyclomaltodextrin glucotransferase, cyclomaltodextrin glycosyltransferase, konchizaimu, alpha-1,4-glucan 4-glycosyltransferase, cyclizing, BMA, CGTase, and neutral-cyclodextrin glycosyltransferase.
Catalytic activities
All of the CGTases can catalyze up to four reactions: cyclization, coupling, disproportionation and hydrolysis. All these activities share the same catalytic mechanism which is common to all glycosyl-hydrolases.
Cyclization is the process through which a linear polysaccharidic chain is cleaved and the two ends of the cleaved fragment are joined to produce a circular dextrin (cyclodextrin or CD): on the basis of the number of sugar residues this circular product is made of three main type of cyclodextrins can be distinguished, α-CD with six residues, β-CD with seven residues and γ-CD with eight residues.
The coupling reaction can be easily described as the reverse process of cyclization: the enzyme cleaves a cyclodextrin to produce a linear dextrin which is subsequently joined to a linear oligosaccharide.
Disproportionation is very similar to coupling, but the cleaved dextrin is not a cyclodextrin, but a linear oligosaccharide that is then joined to a second oligosaccharide.
CGTase also has a weak hydrolyzing activity which consists in cleaving the longer polysaccharidic chains into shorter fragments.
Dextrins are a group of low-molecular-weight carbohydrates produced by the hydrolysis of starch and glycogen. Dextrins are mixtures of polymers of D-glucose units linked by α-(1→4) or α-(1→6) glycosidic bonds.
Cycloamyloses are cyclic α-1,4 linked glucans comprising dozens or hundreds of glucose units. Chemically they are similar to the much smaller cyclodextrins, which are typically composed of 6, 7 or 8 glucose units.
1,4-alpha-glucan-branching enzyme, also known as brancher enzyme or glycogen-branching enzyme is an enzyme that in humans is encoded by the GBE1 gene.
Glycosyltransferases are enzymes that establish natural glycosidic linkages. They catalyze the transfer of saccharide moieties from an activated nucleotide sugar to a nucleophilic glycosyl acceptor molecule, the nucleophile of which can be oxygen- carbon-, nitrogen-, or sulfur-based.
β-Amylase is an enzyme with the systematic name 4-α-D-glucan maltohydrolase. It catalyses the following reaction:
In enzymology, a 1,4-alpha-glucan 6-alpha-glucosyltransferase is an enzyme that catalyzes the chemical reaction that transfers an alpha-D-glucosyl residue in a 1,4-alpha-D-glucan to the primary hydroxyl group of glucose or 1,4-alpha-D-glucan.
Glucan 1,4-α-glucosidase is an enzyme located on the brush border of the small intestine with systematic name 4-α-D-glucan glucohydrolase. It catalyses the following chemical reaction
The enzyme cyclomaltodextrinase (EC 3.2.1.54) catalyzes the chemical reaction
In enzymology, a xyloglucan-specific exo-beta-1,4-glucanase (EC 3.2.1.155) is an enzyme that catalyzes the chemical reaction
In enzymology, an amylosucrase is an enzyme that catalyzes the chemical reaction
In enzymology, a dextrin dextranase is an enzyme that catalyzes the chemical reaction
In enzymology, a 4-alpha-glucanotransferase is an enzyme that catalyzes a chemical reaction that transfers a segment of a 1,4-alpha-D-glucan to a new position in an acceptor carbohydrate, which may be glucose or a 1,4-alpha-D-glucan.
In enzymology, a starch synthase is an enzyme that catalyzes the chemical reaction
In enzymology, a xyloglucan:xyloglucosyl transferase (EC 2.4.1.207) is an enzyme that catalyzes the chemical reaction in which a beta-(1,4) bond in the backbone of a xyloglucan in broken; the xyloglucanyl segment is then transferred to the O4 of the non-reducing terminal glucose residue of either xyloglucan or an oligosaccharide thereof.
In enzymology, an oligosaccharide 4-alpha-D-glucosyltransferase is an enzyme that catalyzes the chemical reaction in which the non-reducing terminal alpha-D-glucose residue is transferred from a 1,4-alpha-D-glucan to the 4-position of an alpha-D-glucan. This enzyme is useful in hydrolyzing oligosaccharides.
Glucanases are enzymes that break down large polysaccharides via hydrolysis. The product of the hydrolysis reaction is called a glucan, a linear polysaccharide made of up to 1200 glucose monomers, held together with glycosidic bonds. Glucans are abundant in the endosperm cell walls of cereals such as barley, rye, sorghum, rice, and wheat. Glucanases are also referred to as lichenases, hydrolases, glycosidases, glycosyl hydrolases, and/or laminarinases. Many types of glucanases share similar amino acid sequences but vastly different substrates. Of the known endo-glucanases, 1,3-1,4-β-glucanase is considered the most active.
Cycloisomaltooligosaccharide glucanotransferase is an enzyme with systematic name (1->6)-alpha-D-glucan:(1->6)-alpha-D-glucan 6-alpha-D-(1->6alpha-D-glucano)-transferase (cyclizing). This enzyme catalyses the following chemical reaction
Glucan 1,4-alpha-maltohydrolase is an enzyme with systematic name 4-alpha-D-glucan alpha-maltohydrolase. This enzyme catalyses the following chemical reaction
Neopullulanase is an enzyme of the alpha-amylase family with systematic name pullulan 4-D-glucanohydrolase (panose-forming). This enzyme principally catalyses the following chemical reaction by cleaving pullulan's alpha-1,4-glucosidic bonds:
Maltodextrin phosphorylase is a phosphorylase enzyme, more specifically one type of glycosyltransferase. Maltodextrin phosphorylase plays a critical role in maltodextrin metabolism in E. coli. This bacterial enzyme, often referred to as MalP, catalyzes the phosphorolysis of an α-1,4-glycosidic bond in maltodextrins, removing the non-reducing glucosyl residues of linear oligosaccharides as glucose-1-phosphate (Glc1P). Phosphorylases are well-regarded for their allosteric effects on metabolism, however MalP exhibits no allosteric properties. It has a higher affinity for linear oligosaccharides than the related glycogen phosphorylase.
References
DePinto JA, Campbell LL (1968). "Purification and properties of the amylase of Bacillus macerans". Biochemistry. 7 (1): 114–20. doi:10.1021/bi00841a015. PMID5758537.
French D, Levine ML, Norberg E, Nordin P, Pazur JH, Wild GM (1954). "Studies on the Schardinger dextrins. VII. Co-substrate specificity in coupling reactions of Macerans amylase". J. Am. Chem. Soc. 76 (9): 2387–2390. doi:10.1021/ja01638a027.
Hehre EJ (1951). "Enzymic Synthesis of Polysaccharides: A Biological type of Polymerization". Advances in Enzymology and Related Areas of Molecular Biology. Advances in Enzymology - and Related Areas of Molecular Biology. Vol.11. pp.297–337. doi:10.1002/9780470122563.ch6. ISBN9780470122563. PMID24540594.{{cite book}}: |journal= ignored (help)
Biwer A, Antranikian G, Heinzle E (September 2002). "Enzymatic production of cyclodextrins". Applied Microbiology and Biotechnology. 59 (6): 609–17. doi:10.1007/s00253-002-1057-x. PMID12226716.
van der Veen BA, Uitdehaag JC, Penninga D, van Alebeek GJ, Smith LM, Dijkstra BW, Dijkhuizen L (March 2000). "Rational design of cyclodextrin glycosyltransferase from Bacillus circulans strain 251 to increase alpha-cyclodextrin production". Journal of Molecular Biology. 296 (4): 1027–38. doi:10.1006/jmbi.2000.3528. PMID10686101.
This page is based on this Wikipedia article Text is available under the CC BY-SA 4.0 license; additional terms may apply. Images, videos and audio are available under their respective licenses.
