EC 2.4.1.33     
Accepted name: mannuronan synthase
Reaction: GDP-α-D-mannuronate + [(1→4)-β-D-mannuronosyl]n = GDP + [(1→4)-β-D-mannuronosyl]n+1
Glossary: poly[β-(1,4)-D-mannuronate] = mannuronan
Other name(s): mannuronosyl transferase; alginate synthase (incorrect); alg8 (gene name); alg44 (gene name); GDP-D-mannuronate:alginate D-mannuronyltransferase
Systematic name: GDP-α-D-mannuronate:mannuronan D-mannuronatetransferase
Comments: The enzyme catalyses the polymerization of β-D-mannuronate residues into a mannuronan polymer, an intermediate in the biosynthesis of alginate. It is found in brown algae and in alginate-producing bacterial species from the Pseudomonas and Azotobacter genera.
References:
1.  Lin, T.-Y. and Hassid, W.Z. Pathway of alginic acid synthesis in the marine brown alga, Fucus gardneri Silva. J. Biol. Chem. 241 (1966) 5284–5297. [PMID: 5954796]
2.  Remminghorst, U. and Rehm, B.H. In vitro alginate polymerization and the functional role of Alg8 in alginate production by Pseudomonas aeruginosa. Appl. Environ. Microbiol. 72 (2006) 298–305. [PMID: 16391057]
3.  Oglesby, L.L., Jain, S. and Ohman, D.E. Membrane topology and roles of Pseudomonas aeruginosa Alg8 and Alg44 in alginate polymerization. Microbiology 154 (2008) 1605–1615. [PMID: 18524915]
[EC 2.4.1.33 created 1972, modified 2015]
 
 
EC 4.2.2.3     
Accepted name: mannuronate-specific alginate lyase
Reaction: Eliminative cleavage of alginate to give oligosaccharides with 4-deoxy-α-L-erythro-hex-4-enuronosyl groups at their non-reducing ends and β-D-mannuronate at their reducing end.
Other name(s): alginate lyase I; alginate lyase; alginase I; alginase II; alginase; poly(β-D-1,4-mannuronide) lyase; poly(β-D-mannuronate) lyase; aly (gene name) (ambiguous); poly[(1→4)-β-D-mannuronide] lyase
Systematic name: alginate β-D-mannuronate—uronate lyase
Comments: The enzyme catalyses the degradation of alginate by a β-elimination reaction. It cleaves the (1→4) bond between β-D-mannuronate and either α-L-guluronate or β-D-mannuronate, generating oligosaccharides with 4-deoxy-α-L-erythro-hex-4-enuronosyl groups at their non-reducing ends and β-D-mannuronate at the reducing end. Depending on the composition of the substrate, the enzyme produces oligosaccharides ranging from two to four residues, with preference for shorter products. cf. EC 4.2.2.11, guluronate-specific alginate lyase.
References:
1.  Davidson, I.W., Lawson, C.J. and Sutherland, I.W. An alginate lysate from Azotobacter vinelandii phage. J. Gen. Microbiol. 98 (1977) 223–229. [PMID: 13144]
2.  Nakada, H.I. and Sweeny, P.C. Alginic acid degradation by eliminases from abalone hepatopancreas. J. Biol. Chem. 242 (1967) 845–851. [PMID: 6020438]
3.  Preiss, J. and Ashwell, G. Alginic acid metabolism in bacteria. I. Enzymatic formation of unsaturated oligosaccharides and 4-deoxy-L-erythro-5-hexoseulose uronic acid. J. Biol. Chem. 237 (1962) 309–316. [PMID: 14488584]
[EC 4.2.2.3 created 1965 as EC 4.2.99.4, transferred 1972 to EC 4.2.2.3, modified 1990, modified 2015]
 
 
EC 4.2.2.11     
Accepted name: guluronate-specific alginate lyase
Reaction: Eliminative cleavage of alginate to give oligosaccharides with 4-deoxy-α-L-erythro-hex-4-enuronosyl groups at their non-reducing ends and α-L-guluronate at their reducing end.
Other name(s): alginase II; guluronate lyase; L-guluronan lyase; L-guluronate lyase; poly-α-L-guluronate lyase; polyguluronate-specific alginate lyase; poly(α-L-1,4-guluronide) exo-lyase; poly(α-L-guluronate) lyase; poly[(1→4)-α-L-guluronide] exo-lyase
Systematic name: alginate α-L-guluronate—uronate lyase
Comments: The enzyme catalyses the degradation of alginate by a β-elimination reaction. It cleaves the (1→4) bond between α-L-guluronate and either α-L-guluronate or β-D-mannuronate, generating oligosaccharides with 4-deoxy-α-L-erythro-hex-4-enuronosyl groups at their non-reducing ends and α-L-guluronate at the reducing end. Depending on the composition of the substrate, the enzyme produces oligosaccharides ranging from two to six residues, with preference for shorter products. cf. EC 4.2.2.3, mannuronate-specific alginate lyase.
References:
1.  Boyd, J. and Turvey, J.R. Isolation of poly-α-L-guluronate lyase from Klebsiella aerogenes. Carbohydr. Res. 57 (1977) 163–171. [PMID: 332364]
2.  Davidson, I.W., Sutherland, I.W. and Lawson, C.J. Purification and properties of an alginate lyase from a marine bacterium. Biochem. J. 159 (1976) 707–713. [PMID: 1008828]
[EC 4.2.2.11 created 1990, modified 2015]
 
 
EC 4.2.2.26     
Accepted name: oligo-alginate lyase
Reaction: Cleavage of poly(4-deoxy-α-L-erythro-hexopyranuronoside) oligosaccharides with 4-deoxy-α-L-erythro-hex-4-enopyranuronosyl groups at their non-reducing ends into 4-deoxy-α-L-erythro-hex-4-enopyranuronate monosaccharides.
Other name(s): aly (gene name) (ambiguous); oalS17 (gene name); oligoalginate lyase; exo-oligoalginate lyase
Systematic name: alginate oligosaccharide 4-deoxy-α-L-erythro-hex-4-enopyranuronate-(1→4)-hexananopyranuronate lyase
Comments: The enzyme degrades unsaturated oligosaccharides produced by the action of alginate lyases (EC 4.2.2.3 and EC 4.2.2.11) on alginate, by repeatedly removing the unsaturated residue from the non-reducing end until only unsaturated monosaccharides are left. The enzyme catalyses a β-elimination reaction, generating a new unsaturated non-reducing end after removal of the pre-existing one.
References:
1.  Hashimoto, W., Miyake, O., Momma, K., Kawai, S. and Murata, K. Molecular identification of oligoalginate lyase of Sphingomonas sp. strain A1 as one of the enzymes required for complete depolymerization of alginate. J. Bacteriol. 182 (2000) 4572–4577. [PMID: 10913091]
2.  Kim, H.T., Chung, J.H., Wang, D., Lee, J., Woo, H.C., Choi, I.G. and Kim, K.H. Depolymerization of alginate into a monomeric sugar acid using Alg17C, an exo-oligoalginate lyase cloned from Saccharophagus degradans 2-40. Appl. Microbiol. Biotechnol. 93 (2012) 2233–2239. [PMID: 22281843]
3.  Jagtap, S.S., Hehemann, J.H., Polz, M.F., Lee, J.K. and Zhao, H. Comparative biochemical characterization of three exolytic oligoalginate lyases from Vibrio splendidus reveals complementary substrate scope, temperature, and pH adaptations. Appl. Environ. Microbiol. 80 (2014) 4207–4214. [PMID: 24795372]
4.  Wang, L., Li, S., Yu, W. and Gong, Q. Cloning, overexpression and characterization of a new oligoalginate lyase from a marine bacterium, Shewanella sp. Biotechnol. Lett. 37 (2015) 665–671. [PMID: 25335746]
[EC 4.2.2.26 created 2015]
 
 
EC 4.2.99.4      
Transferred entry: alginate lyase. Now EC 4.2.2.3, poly(β-D-mannuronate) lyase
[EC 4.2.99.4 created 1965, deleted 1972]
 
 
EC 5.1.3.37     
Accepted name: mannuronan 5-epimerase
Reaction: [mannuronan]-β-D-mannuronate = [alginate]-α-L-guluronate
Glossary: mannuronan = a linear polymer of β-D-mannuronate residues linked by (1-4) linkages
alginate = a linear polymer of β-D-mannuronate residues linked by (1-4) linkages, with variable amounts of its C-5 epimer α-L-guluronate.
Other name(s): algG (gene name); alginate epimerase; C5-mannuronan epimerase; mannuronan C-5-epimerase
Systematic name: [mannuronan]-β-D-mannuronate 5-epimerase
Comments: The enzyme epimerizes the C-5 bond in some β-D-mannuronate residues in mannuronan, converting them to α-L-guluronate residues, and thus modifying the mannuronan into alginate. It is found in brown algae and alginate-producing bacterial species from the Pseudomonas and Azotobacter genera.
References:
1.  Franklin, M.J., Chitnis, C.E., Gacesa, P., Sonesson, A., White, D.C. and Ohman, D.E. Pseudomonas aeruginosa AlgG is a polymer level alginate C5-mannuronan epimerase. J. Bacteriol. 176 (1994) 1821–1830. [PMID: 8144447]
2.  Morea, A., Mathee, K., Franklin, M.J., Giacomini, A., O'Regan, M. and Ohman, D.E. Characterization of algG encoding C5-epimerase in the alginate biosynthetic gene cluster of Pseudomonas fluorescens. Gene 278 (2001) 107–114. [PMID: 11707327]
3.  Nyvall, P., Corre, E., Boisset, C., Barbeyron, T., Rousvoal, S., Scornet, D., Kloareg, B. and Boyen, C. Characterization of mannuronan C-5-epimerase genes from the brown alga Laminaria digitata. Plant Physiol. 133 (2003) 726–735. [PMID: 14526115]
4.  Jain, S., Franklin, M.J., Ertesvag, H., Valla, S. and Ohman, D.E. The dual roles of AlgG in C-5-epimerization and secretion of alginate polymers in Pseudomonas aeruginosa. Mol. Microbiol. 47 (2003) 1123–1133. [PMID: 12581364]
5.  Douthit, S.A., Dlakic, M., Ohman, D.E. and Franklin, M.J. Epimerase active domain of Pseudomonas aeruginosa AlgG, a protein that contains a right-handed β-helix. J. Bacteriol. 187 (2005) 4573–4583. [PMID: 15968068]
6.  Wolfram, F., Kitova, E.N., Robinson, H., Walvoort, M.T., Codee, J.D., Klassen, J.S. and Howell, P.L. Catalytic mechanism and mode of action of the periplasmic alginate epimerase AlgG. J. Biol. Chem. 289 (2014) 6006–6019. [PMID: 24398681]
[EC 5.1.3.37 created 2015]
 
 


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