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Polysaccharide Lyase Family 44
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| Polysaccharide Lyase Family PL44 | |
| 3D Structure | parallel β-helix (AlphaFold) |
| Mechanism | poly-mannuronate preferred |
| Charge neutraliser | not known |
| Active site residues | not known |
| CAZy DB link | |
| https://www.cazy.org/PL44.html | |
Substrate specificities
Members of polysaccharide lyase family 44 have been shown to exhibit alginate lyase activity. The first member of this family is Aly44A, which originates from the bacterium Bacillus sp. FJAT-50079. (Genbank number WP_213137828.1). A total of 126 homologous sequences of Aly44A were identified by utilizing the BLASTp (with sequence coverage > 70% and identity > 40%) and CD-Hit tools. Meanwhile, four homologs of Aly44A exhibited the ability to degrade alginate (Zhou et al., 2024).
Kinetics and Mechanism
The kinetic analysis showed that Aly44A exhibited higher conversion efficiency and a stronger affinity for polyM compared to polyG, indicating Aly44A was polyM-preferred. In contrast to bifunctional alginate lyases, which exhibited no preference for polyG or polyM, Aly44A showed superior potential in the preparation of alginate oligosaccharides consisting of M-blocks. It showed that Aly44A had a higher affinity and catalytic efficiency towards the polyM region of the longer-chain alginate (Zhou et al., 2024).
Action Pattern
Based on the analysis of the action pattern, it showed that Aly44A was polyM-preferred. Aly44A was verified to exhibit a random endo-acting lyase activity to alginate. The final products of degradation were alginate oligosaccharides with DP 2-8, the main products of degradation were AOS with DP 2-4 as detected by UPSEC-MS (Zhou et al., 2024).
Catalytic Residues
No catalytic residues have been identified in this polysaccharide lyase family at present.
Three-dimensional structures
The structure of Aly44A was predicted to be a parallel β-helix by AlphaFold2 (Zhou et al., 2024).
Family Firsts
- First description of catalytic activity
The alginate lyase Aly44A was the first member of the family PL44 to be identified and characterized.
- First stereochemistry determination
- Not yet identified.
- First catalytic nucleophile identification
- Not yet identified.
- First general acid/base residue identification
- Not yet identified.
- First 3-D structure
- Not yet identified.