EC Number   |
General Information |
Reference |
|---|
   2.4.1.140 | evolution |
the enzyme belongs to the CAZy glycoside hydrolase family 70 (GH70) |
-, 760170 |
| 2.4.1.140 | evolution |
the enzyme belongs to the glycoside hydrolase family 70 (GH70) |
-, 758556 |
| 2.4.1.140 | more |
analysis of structural determinants involved in the linkage specificity of alternansucrase (ASR), overview. ASR displays two different acceptor subsites in the prolongation of its subsites -1 and +1. The first one is defined by Trp675, a residue of subsite +2, and orients acceptor binding exclusively toward alpha-1,6 linkage synthesis. The second binding site comprises Asp772 and Trp543, two residues defining the +2' and +3' subsites, respectively, which are critical for alpha-1,3 linkage formation. It is proposed that the interplay between these two acceptor sites controls alternance. The enzyme is predicted to adopt the same fold as the other glucansucrases and the same alpha-retaining mechanism involving the contribution of Asp635, Glu673, and Asp767. These amino acids play the role of, respectively, the nucleophile, acid/base catalyst, and transition state stabilizer (TSS) implicated in the formation of the beta-D-glucosyl-enzyme intermediate. Kinetic study conducted with ASR C-APY-del shows that both high molar mass and low molar mass alternan populations are formed in the early stage of the reaction, suggesting that ASR follows a semiprocessive mechanism of polymerization. Three-dimensional structure analysis, overview |
-, 758556 |
| 2.4.1.140 | more |
catalytic mechanism of di-glycosyl-stevioside synthesis, overview |
-, 759575 |
| 2.4.1.140 | physiological function |
alternansucrase (ASR) is an alpha-transglucosylase capable of catalyzing high and low molar mass alternan, an alpha-glucan comprising alternating alpha-1,3 and alpha-1,6 linkages in its linear chain. ASR also catalyzes transglucosylation from sucrose to many different types of sugar acceptors: methyl-alpha-D-glucoside, maltose, maltodextrin, maltitol, isomaltooligosaccharides, cellobiose, melibiose, raffinose, gentiobiose, and lactose, and produces glucosylated products showing interesting prebiotic properties |
-, 758556 |
| 2.4.1.140 | physiological function |
alternansucrase catalyses the sequential transfer of glucose residues from sucrose onto another sucrose molecule to form a long chain polymer, known as alternan. The insoluble polymer alternan has alternating alpha-1,6 and alpha-1,3 glycosidic linkages as has been judged by using 13C NMR spectroscopy and methylation analysis, partially hydrolysed product analysis, and enzymatic analysis |
-, 760170 |
