Fig. 2: Function and sequence orthology.
From: A metagenomic ‘dark matter’ enzyme catalyses oxidative cellulose conversion
a, Boosting effect on the saccharification of pretreated sugarcane bagasse, microcrystalline cellulose and amorphous cellulose when CelOCE is combined with a cellulolytic enzyme cocktail. Data are the mean ± s.d. from three independent experiments. Statistical significance was determined by one-way analysis of variance (ANOVA) with Tukey’s post hoc test (**P < 0.01). Percentages indicate the difference between treatments. b, High-performance anion-exchange chromatography with pulsed amperometric detection (HPAEC–PAD) profiles of reactions containing reductant and enzymes CelOCE (dark green line), KdgF (orange line) and BacB (blue line). Control reactions using only sugarcane bagasse (dark grey line), only ASC (grey line), sugarcane bagasse and CelOCE, no ASC (light green line), sugarcane bagasse and ASC (light grey line) and with inactivated enzyme (grey–blue line) are also shown. Standard C1-oxidized and non-oxidized cellooligosaccharides are represented by black lines. DP, degree of polymerization; ox, oxidized. c,d, Amorphous (c) and microcrystalline cellulose (d) binding isotherms comparing the enzyme in the presence or absence of a reductant (ASC). The binding isotherms for PASC were fitted using the Langmuir–Freundlich model. The fit for CelOCE without ASC yielded n = 2.5 (n, Langmuir–Freundlich coefficient) and R2 = 0.99, whereas the fit for CelOCE with ASC resulted in n = 2.1 and R2 = 0.99. Data are the mean ± s.d. from three independent experiments. e, SSN depicting three distinct isofunctional clusters of the reference proteins BacB (Protein Data Bank (PDB) ID: 3H7J), KdgF (PDB ID: 5FPZ) and CelOCE (this study). Connections between nodes indicate at least 30% sequence identity with an alignment e-value cut-off of 1 × 10–5.
