5.1.3.37 hepta(beta-(1->4)-D-mannuronate)acid poor substrate Azotobacter vinelandii ? - ? 433804 5.1.3.37 hexa(beta-(1->4)-D-mannuronate) poor substrate Azotobacter vinelandii ? - ? 433809 5.1.3.37 additional information alginates from Durvillea antarctica, Lessonia nigrescens, Laminaria hyperborea and a bacterial mannuronan are epimerized. The enzyme converts the M blocks into MGM sequences leaving the G-blocks intact Azotobacter vinelandii ? - ? 89 5.1.3.37 additional information enzyme exhibits a non-random mode of action when acting on mannuronan and alginates of various monomeric compositions. On average 10 residues are epimerised for each enzyme-substrate encounter. A hexameric oligomer is the minimum size to accommodate activity. For hexa-, hepta- and octameric substrates the third M residue from the nonreducing end is epimerised first Azotobacter vinelandii ? - ? 89 5.1.3.37 additional information epimerization reaction is detected only when acetyl groups are removed from the poly-D-mannuronate substrate, suggesting that AlgG epimerization activity in vivo may be sensitive to acetylation of the D-mannuronan residues Pseudomonas aeruginosa ? - ? 89 5.1.3.37 additional information isoform AlgE7 degrades M-rich alginates and a relatively G-rich alginate from the brown algae Macrocystis pyrifera most effectively, producing oligomers of 4 (mannuronan) to 7 units. The sequences cleaved are mainly G-MM and/or G-GM. G-moieties dominate at the reducing ends even when mannuronan is used as substrate, so the AlgE7 lyase/epimerase probably stimulates the lyase pathway, indicating a complex interplay between the two activities Azotobacter vinelandii ? - ? 89 5.1.3.37 additional information the enzyme either slides along the alginate chain during catalysis or recognizes a pre-existing G residue as a preferred substrate in its consecutive attacks Azotobacter vinelandii ? - ? 89 5.1.3.37 additional information the minimal substrate contains 9 monosaccharide residues. Tracts of adjacent guluronate residues are readily formed. The reaction reaches an apparent equilibrium when the guluronate composition of the polymer is 75% Pseudomonas aeruginosa ? - ? 89 5.1.3.37 additional information effect of ManC5-Es on alginate structures, overview. Alginate in brown algae is first formed as a polysaccharide chain containing mannuronic acid residues only. These are subsequently transformed by the ManC5-E into guluronic acid residues, generating distinct patterns arranged in regions of MM-, GG- and MG-blocks (beta-D-mannuronic acid (M) and alpha-L-guluronic acid (G) residues). Patterns containing large stretches of adjacent guluronic acid residues (GG-blocks) form structured interchain associations in the presence of Ca2+ ions. These interchain junctions have the so-called egg-box conformation and are responsible for the gelling properties of alginate and cell-wall strengthening Ectocarpus siliculosus ? - ? 89 5.1.3.37 additional information effect of ManC5-Es on alginate structures, overview. Alginate in brown algae is first formed as a polysaccharide chain containing mannuronic acid residues only. These are subsequently transformed by the ManC5-E into guluronic acid residues, generating distinct patterns arranged in regions of MM-, GG- and MG-blocks (beta-D-mannuronic acid (M) and alpha-L-guluronic acid (G) residues). Patterns containing large stretches of adjacent guluronic acid residues (GG-blocks) form structured interchain associations in the presence of Ca2+ ions. These interchain junctions have the socalled egg-box conformation and are responsible for the gelling properties of alginate and cell-wall strengthening Ectocarpus siliculosus ? - ? 89 5.1.3.37 additional information alginate binding ability of the R-modules of AlgE4 by NMR and isothermal titration calorimetry, overview. Titration of the R-modules with defined alginate oligomers shows strong interaction between AlgE4R and both oligo-M and MG Azotobacter vinelandii ? - ? 89 5.1.3.37 additional information alginate binding ability of the R-modules of AlgE6 by NMR and isothermal titration calorimetry, overview. Titration of the R-modules with defined alginate oligomers shows no interaction between these oligomers and the individual R-modules from AlgE6. Acombination of all three R-modules from AlgE6 shows weak interaction with long M-oligomers Azotobacter vinelandii ? - ? 89 5.1.3.37 additional information all the mannuronan C5-epimerases of Azotobacter vinelandii show differences in substrate specificity and concentration of calcium ions needed for full activity Azotobacter vinelandii ? - ? 89 5.1.3.37 additional information all the mannuronan C5-epimerases of Azotobacter vinelandii show differences in substrate specificity and concentration of calcium ions needed for full activity. AlgE4 acts processively by sliding along the alginate chain and epimerizing every second residue, generating alternating MG-sequences. Epimerization of calcium-alginate gel beads and of oxidized/reduced polyM and acetylated alginate by recombinant enzyme, overview. The enzyme is tested on internally gelled high-M calcium-alginate cylinders Azotobacter vinelandii ? - ? 89 5.1.3.37 additional information all the mannuronan C5-epimerases of Azotobacter vinelandii show differences in substrate specificity and concentration of calcium ions needed for full activity. Epimerization of calcium-alginate gel beads and of oxidized/reduced polyM and acetylated alginate by recombinant enzyme, overview. The enzyme is tested on internally gelled high-M calcium-alginate cylinders, AlgE6 and AlgE64 show a gradient in the G-content which decreases from the outer wall towards the core of the cylinder, while AlgE6A gives the same degree of epimerization across the whole gel cylinder. GG-dyads content also follows the same trend Azotobacter vinelandii ? - ? 89 5.1.3.37 additional information all the mannuronan C5-epimerases of Azotobacter vinelandii show differences in substrate specificity and concentration of calcium ions needed for full activity. Epimerization of calcium-alginate gel beads and of oxidized/reduced polyM and acetylated alginate by recombinant enzyme, overview. The enzyme is tested on internally gelled high-M calcium-alginate cylinders: AlgE1 shows a gradient in the G-content which decreases from the outer wall towards the core of the cylinder. GG-dyads content also follows the same trend Azotobacter vinelandii ? - ? 89 5.1.3.37 additional information Ca2+-induced gel precipitation assay. 1H-NMR spectroscopy of rSjC5-VI-treated polyM reveals alternate epimerization of beta-D-mannuronic acid to alpha-L-guluronic acid for the MC5E activity in eukaryotes. Gelation is enhanced by changes in the M/G ratio. The optimum in vitro polyM concentration is determined at 0.25% Saccharina japonica ? - ? 89 5.1.3.37 additional information subatrate specificity and change of blockiness of the active recombinant His-tagged catalytic domain is analyzed by NMR study, overview Ectocarpus siliculosus ? - ? 89 5.1.3.37 additional information epimerization reaction is detected only when acetyl groups are removed from the poly-D-mannuronate substrate, suggesting that AlgG epimerization activity in vivo may be sensitive to acetylation of the D-mannuronan residues Pseudomonas aeruginosa ATCC 15692 ? - ? 89 5.1.3.37 octa(beta-(1->4)-D-mannuronate) - Azotobacter vinelandii ? - ? 434078 5.1.3.37 [alginate]-beta-D-mannuronate - Azotobacter vinelandii [alginate]-alpha-L-guluronate - ? 434484 5.1.3.37 [alginate]-beta-D-mannuronate - Azotobacter vinelandii [alginate]-alpha-L-guluronate during epimerization of alginate, the fraction of GMG blocks increases linearly as a function of the total fraction of G residues and comparably much faster than that of MMG blocks ? 434484 5.1.3.37 [alginate]-beta-D-mannuronate - Azotobacter vinelandii [alginate]-alpha-L-guluronate reaction product of AlgE1 is a mixture of blocks of continuous G residues (G-blocks) and blocks containing alternating M and G residues (MG-blocks) ? 434484 5.1.3.37 [alginate]-beta-D-mannuronate alginate, isolated from Azotobacter vinelandii, contains 95% of D-mannuronic acid and 5% of L-guluronic acid residues Azotobacter vinelandii [alginate]-alpha-L-guluronate - ? 434484 5.1.3.37 [mannuronan]-beta-D-mannuronate - Ectocarpus siliculosus [alginate]-alpha-L-guluronate - r 434487 5.1.3.37 [mannuronan]-beta-D-mannuronate - Azotobacter vinelandii [alginate]-alpha-L-guluronate - ? 434487 5.1.3.37 [mannuronan]-beta-D-mannuronate - Azotobacter vinelandii [alginate]-alpha-L-guluronate - r 434487 5.1.3.37 [mannuronan]-beta-D-mannuronate - Saccharina japonica [alginate]-alpha-L-guluronate - r 434487 5.1.3.37 [mannuronan]-beta-D-mannuronate - Pseudomonas aeruginosa [alginate]-alpha-L-guluronate initial binding of the polymeric substrate to the enzyme is followed by a slow step that aligns the substrate more precisely for reaction. The substrate is moved into register with active site residues before catalysis took place. Release of the product also is slow r 434487 5.1.3.37 [mannuronan]-beta-D-mannuronate - Pseudomonas aeruginosa [alginate]-alpha-L-guluronate isoform AlgG acts as a polymer-level mannuronan C5-epimerase ? 434487 5.1.3.37 [mannuronan]-beta-D-mannuronate - Azotobacter vinelandii [alginate]-alpha-L-guluronate very efficient conversion of poly(mannuronic acid) into a polymer containing 42% of guluronic acid ? 434487 5.1.3.37 [mannuronan]-beta-D-mannuronate - Pseudomonas aeruginosa ATCC 15692 [alginate]-alpha-L-guluronate isoform AlgG acts as a polymer-level mannuronan C5-epimerase ? 434487