Enzymatic modifications of sugar in supercritical carbon dioxide

Poster (2009, July 07)

Carbohydrates esters are non-ionic surfactants that have a wide range of commercial applications in cosmetic, food and pharmaceutical industry. They are produced from renewable and inexpensive raw ... [more ▼]

Carbohydrates esters are non-ionic surfactants that have a wide range of commercial applications in cosmetic, food and pharmaceutical industry. They are produced from renewable and inexpensive raw materials, are bio-degradable and non-toxic. Chemical synthesis of sugar esters is generally performed at a high temperature in the presence of an alkaline catalyst lead-ing to a mixture of products. In this respect, the corresponding enzyme-catalyzed processes in non-conventional media are more selective. For this purpose, lipases are the most useful enzymes. Moreover, supercritical carbon dioxide (SC-CO2) constitutes an interesting alternative to the organic solvents used in the domain as it is considered to be environmentally frien-dlier and safer. For example, its use reduces the contamination of the final products with residual solvents. This property is particularly valued in food, cosmetic and pharmaceutical industry. Our work consists to carry out lipase catalyzed sugar modifications in SC-CO2 and to compare the results with those obtained in organic solvents. The effect of these two different media on the enzyme stability and the yield will be described here. Moreover, the impact of various factors such as pressure, temperature, enzyme form (free or immobilized), use of co-solvent, on the course of the sugar esterification will be discussed. [less ▲]

Study of thermomyces ianuginosa lipase in the presence of tributyrylglycerol and water

in Biophysical Journal (2009), 96(12), 4814-4825

The Thermomyces lanuginosa lipase has been extensively studied in industrial and biotechnological research because of its potential for triacylglycerol transformation. This protein is known to catalyze ... [more ▼]

The Thermomyces lanuginosa lipase has been extensively studied in industrial and biotechnological research because of its potential for triacylglycerol transformation. This protein is known to catalyze both hydrolysis at high water contents and transesterification in quasi-anhydrous conditions. Here, we investigated the Thermomyces lanuginosa lipase structure in solution in the presence of a tributyrin aggregate using 30 ns molecular-dynamics simulations. The water content of the active-site groove was modified between the runs to focus on the protein-water molecule interactions and their implications for protein structure and protein-lipid interactions. The simulations confirmed the high plasticity of the lid fragment and showed that lipid molecules also bind to a secondary pocket beside the lid. Together, these results strongly suggest that the lid plays a role in the anchoring of the protein to the aggregate. The simulations also revealed the existence of a polar channel that connects the active-site groove to the outside solvent. At the inner extremity of this channel, a tyrosine makes hydrogen bonds with residues interacting with the catalytic triad. This system could function as a pipe (polar channel) controlled by a valve (the tyrosine) that could regulate the water content of the active site. [less ▲]

Chemical and enzymatical modifications of sugar derived from lignocellulose

Poster (2009, January)

Actually, biorefinery is increasingly considered as a promising alternative to petroleum chemistry, since it aims at not only the replacement of fossil energy but also the development of chemicals from ... [more ▼]

Actually, biorefinery is increasingly considered as a promising alternative to petroleum chemistry, since it aims at not only the replacement of fossil energy but also the development of chemicals from biomass, with applications such as detergents, phytopharmaceutics, solvents, plastics, etc. The valorisation of carbohydrates from renewable raw materials is currently the subject of numerous researches. In this context, the synthesis of new surfactants derived from the sugars issued from the lignocellulose hydrolysis was undertaken by chemical or enzymatic routes. In this poster, the examples of glucose, cellobiose and uronic acids will be discussed. Whatever the way used, the reaction conditions (use of a catalyst, protection/deprotection steps, type of solvent, presence of co-solvent, reactant concentrations, etc) were optimized to yield a panel of carbohydrate derivatives (some examples of the structures obtained are given above). These differ by the nature of the alkyl chain (in length and in degree of saturation), the type of chemical bond (amide, ester, thioester, acetal), and the position of substitution. The impact of these differences on the techno-functional properties of these modified sugars will be evaluated. [less ▲]

Set-up of Z- and E-guggulsterones purification method from guggul-gum extracts by liquid chromatography and study of their activities on human preadipocytes differentiation

Poster (2009)

The rising prevalence of obesity within both industrialized and emerging societies is a major public health problem. Indeed obesity is a usual risk factor in the development of metabolic and ... [more ▼]

The rising prevalence of obesity within both industrialized and emerging societies is a major public health problem. Indeed obesity is a usual risk factor in the development of metabolic and cardiovascular diseases which nowadays rank among the highest causes of premature death. Therefore, modulating fat mass expansion represents a worldwide challenge. In this context, adipocyte differentiation, which corresponds to the cellular transition of a fibroblastic cell (the preadipocyte) to a highly specialized cell accumulating triglycerides (the adipocyte), is a decisive process in the expansion of adipose tissue during life span and consequently, in the development of obesity. Adipogenesis markers such as PPARg2, C/EBPa, lipoprotein lipase (LPL), perilipin (PLIN) and the adipokines (leptin and adinopectin) are known to be expressed throughout the different stages of adipocyte differentiation. Guggulsterones are the principal bioactive steroidal components found in the oleoresin (guggul gum) collected from the indian guggul tree, Commiphora mukul (Hook, ex Stocks) Engl. The objective of this study was to investigate the effects of the two purified diastereoisomeric forms of guggulsterones (Z- and E-) on the human preadipocytes proliferation and differentiation. [less ▲]

The effects of purified Z- and E-guggulsterones from guggul-gum extract on human preadipocytes proliferation and differentiation through the study of gene expression of adipose markers.

Poster (2009)

The rising prevalence of obesity within both industrialized and emerging societies is a major public health problem. Indeed obesity is a usual risk factor in the development of metabolic and ... [more ▼]

The rising prevalence of obesity within both industrialized and emerging societies is a major public health problem. Indeed obesity is a usual risk factor in the development of metabolic and cardiovascular diseases which nowadays rank among the highest causes of premature death. Therefore, modulating fat mass expansion represents a worldwide challenge. In this context, adipocyte differentiation, which corresponds to the cellular transition of a fibroblastic cell (the preadipocyte) to a highly specialized cell accumulating triglycerides (the adipocyte), is a decisive process in the expansion of adipose tissue during life span and consequently, in the development of obesity. Adipogenesis markers such as PPARg2, C/EBPa, lipoprotein lipase (LPL), perilipin (PLIN) and the adipokines (leptin and adinopectin) are known to be expressed throughout the different stages of adipocyte differentiation. Guggulsterones are the principal bioactive steroidal components found in the oleoresin (guggul gum) collected from the indian guggul tree, Commiphora mukul (Hook, ex Stocks) Engl. The objective of this study was to investigate the effects of the two purified diastereoisomeric forms of guggulsterones (Z- and E-) on the human preadipocytes proliferation and differentiation. [less ▲]

The use of Macronet resins to recover γ-decalactone produced by Rhodotorula aurantiaca from the culture broth

Poster (2009)

The objective of this study was to recover the γ-decalactone produced by R. aurantiaca from the culture broth using three Macronet resins (MN-100, MN-102 and MN-202).

Contribution to the study of semiochemical slow release formulations. Development of flash chromatographic methods.

Poster (2009)

Glucosinolates and their measurement

Conference (2009)

Wheat root ecophysiology: understanding communication between wheat root system and soil microorganisms.

Poster (2009)

Studies leading to a better understanding of the mechanisms involved in the communication between soil microorganisms and root system can potentially lead to improved fertility management strategies. Up ... [more ▼]

Studies leading to a better understanding of the mechanisms involved in the communication between soil microorganisms and root system can potentially lead to improved fertility management strategies. Up to now, the characterization of such interactions has been mainly focused on root exsudates but volatile organic compounds (VOC) also play a role as chemical messengers in positive interactions occurring in the rhizosphere. We aim to better understand the VOC-mediated chemical ecophysiology of soil. Wheat (Triticum aestivum L.) was chosen in this project based on its importance for food production and industrial applications. [less ▲]

Interesterification of rapeseed oil with anhydrous milk fat and its stearin fraction

Poster (2009)

Rapeseed oil (RO) (a choice source of unsaturation-rich residues) was used in the present study to enrich anhydrous milk fat (AMF) with unsaturated C18 fatty acids (FA) (oleic, linoleic and linolenic ... [more ▼]

Rapeseed oil (RO) (a choice source of unsaturation-rich residues) was used in the present study to enrich anhydrous milk fat (AMF) with unsaturated C18 fatty acids (FA) (oleic, linoleic and linolenic acids). Comparatively, one “harder” fraction of AMF underwent the same reaction. The physico-chemical properties modifications induced by the reaction were followed. The compositional changes are reported in this first part and the consequent physical modifications are presented in a second part. [less ▲]