EC Number   |
General Information |
Reference  |
|---|
    5.1.3.37 | more |
transcript expression as a function of the developmental program of the brown alga, Ectocarpus sp. |
747915 |
| 5.1.3.37 | physiological function |
mannuronan C5-epimerases (ManC5-Es) catalyze in brown algae the remodeling of alginate, a major cell-wall component which is involved in many biological functions in these organisms. ManC5-Es are present as large multigenic families in brown algae, likely indicating functional specificities and specializations. ManC5-Es control the distribution pattern of (1-4)-linked beta-D-mannuronic acid (M) and alpha-L-guluronic acid (G) residues in alginates, giving rise to widely different polysaccharide compositions and sequences, depending on tissue, season, age, or algal species. 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. 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 |
747915 |
| 5.1.3.37 | evolution |
the bacterium Azotobacter vinelandii produces a family of seven secreted and calcium-dependent mannuronan C-5 epimerases (AlgE1-7) |
748180 |
| 5.1.3.37 | more |
alginate epimerases consist of catalytic and noncatalytic domains. The noncatalytic domains of AlgE4 and AlgE6 possess different alginate binding behavior despite highly similar structures. Noncatalytic subunits of AlgE6 and AlgE4 influence the product specificity of the catalytic domain |
748180 |
| 5.1.3.37 | physiological function |
alginate is produced as poly-M and then certain M residues are converted to G by epimerases acting on the polymer level. The alginate-producing bacterium Azotobacter vinelandii has one periplasmic epimerase, which incorporates single G residues into the alginate during secretion of the polymer. In addition, Azotobacter vinelandii produces seven extracellular C-5 alginate epimerases called AlgE1-7. Each of the epimerases convert mannuronic acid to guluronic acid in different patterns. The secreted and calcium-dependent mannuronan C-5 epimerases in Azotobacter vinelandii are responsible for epimerization of beta-D-mannuronic acid (M) to alpha-L-guluronic acid (G) in alginate polymers |
748180 |
| 5.1.3.37 | physiological function |
alginate is produced as poly-M and then certain M residues are converted to G by epimerases acting on the polymer level. The alginate-producing bacterium Azotobacter vinelandii has one periplasmic epimerase, which incorporates single G residues into the alginate during secretion of the polymer. In addition, Azotobacter vinelandii produces seven extracellular C-5 alginate epimerases called AlgE1-7. Each of the epimerases converts mannuronic acid to guluronic acid in different patterns. The secreted and calcium-dependent mannuronan C-5 epimerases in Azotobacter vinelandii are responsible for epimerization of beta-D-mannuronic acid (M) to alpha-L-guluronic acid (G) in alginate polymers |
748180 |
