The novel thermostable cellulose-degrading enzyme DtCel5H from Dictyoglomus thermophilum: crystallization and X-ray crystallographic analysis

Cellulose-based products constitute the great majority of municipal waste, and applications of cellulases in the conversion of waste biomass to biofuels will be a key technology in future biorefineries. Currently, multi-enzymatic pre-treatment of biomass is a crucial step in making carbohydrates more accessible for subsequent fermentation. Using bioinformatics analysis, endo-β-(1,4)-glucanase from Dictyoglomus thermophilum (DtCel5H) was identified as a new member of glycosyl hydrolase family 5. The gene encoding DtCel5H was cloned and the recombinant protein was overexpressed for crystallization and biophysical studies. Here, it is shown that this enzyme is active on cellulose substrates and is highly thermostable. Crystals suitable for crystallographic investigations were also obtained in different crystallization conditions. In particular, ordered crystals of DtCel5H were obtained using either ammonium sulfate or polyethylene glycol (PEG) as a precipitant agent. The crystals obtained in the presence of ammonium sulfate belonged to space group P32, with unit-cell parameters a = 73.1, b = 73.1, 73.1, c = 127.8 Å, and diffracted to 1.5 Å resolution, whereas the second crystal form belonged to the orthorhombic space group P212121, with unit-cell parameters a = 49.3, b = 67.9, c = 103.7 Å, and diffracted to 1.6 Å resolution. The crystal structure was solved in both space groups using molecular-replacement methods. Structure–activity and structure–stability studies of DtCel5H will provide insights for the design of high-performance enzymes.

Chemo-enzymatic synthesis of 3-O- (β-d-glycopyranosyl)-sn-glycerols and their evaluation as preservative in cosmetics

Abstractd-Glycopyranosyl glycerols are common natural products and exhibit strong biological properties, notably as moisturizing agents in cosmetics. Their chemical synthesis remains tedious thus decreasing their potential industrial and economic development, as well as the study of their structure-function relationships. In this work, the chemo-enzymatic synthesis of three enantiopure 3-O-(β-d-glycopyranosyl)-sn-glycerols was efficiently performed using an original glycosidase from Dictyoglomus thermophilum and their preservatives properties were assessed using a challenge test method. Amongst them, the 3-O-(β-d-glucopyranosyl)-sn-glycerol exhibited a specific anti-fungus activity.