Lipase catalyzed synthesis of l-alanyl esters of carbohydrates

Lactose esters: synthesis and biotechnological applications

Biodegradable nonionic sugar esters-based surfactants have been gaining more and more attention in recent years due to their chemical plasticity that enables the various applications of these molecules. In this review, various synthesis methods and biotechnological implications of lactose esters (LEs) uses are considered. Several chemical and enzymatic approaches are described for the synthesis of LEs, together with their applications, i.e. function in detergents formulation and as additives that not only stabilize food products but also protect food from undesired microbial contamination. Further, this article discusses medical applications of LEs in cancer treatment, especially their uses as biosensors, halogenated anticancer drugs, and photosensitizing agents for photodynamic therapy of cancer and photodynamic inactivation of microorganisms.

Sugar ester surfactants: enzymatic synthesis and applications in food industry

Sugar esters are non-ionic surfactants that can be synthesized in a single enzymatic reaction step using lipases. The stability and efficiency of lipases under unusual conditions and using non-conventional media can be significantly improved through immobilization and protein engineering. Also, the development of de novo enzymes has seen a significant increase lately under the scope of the new field of synthetic biology. Depending on the esterification degree and the nature of fatty acid and/or sugar, a range of sugar esters can be synthesized. Due to their surface activity and emulsifying capacity, sugar esters are promising for applications in food industry.

Specific and non-specific enzymes for furanosyl-containing conjugates: biosynthesis, metabolism, and chemo-enzymatic synthesis

There is no doubt now that the synthesis of compounds of varying complexity such as saccharides and derivatives thereof continuously grows with enzymatic methods. This review focuses on recent basic knowledge on enzymes specifically involved in the biosynthesis and degradation of furanosyl-containing polysaccharides and conjugates. Moreover, and when possible, biocatalyzed approaches, alternative to standard synthesis, will be detailed in order to strengthen the high potential of these biocatalysts to go further with the preparation of rare furanosides. Interesting results will be also proposed with chemo-enzymatic processes based on nonfuranosyl-specific enzymes.

Biocatalysis for the production of carbohydrate esters

Carbohydrate fatty acid esters are nonionic biosurfactants, which can be synthesized from the esterification of mono- or oligosaccharides by enzymatic catalysis. These esters are increasingly used as important commodity chemicals, such as low calorific sweeteners and biosurfactants in food, pharmaceutical and cosmetic industries. Recently, some of the ester derivatives have shown their therapeutic potential with antitumor activity, plant growth inhibition and antibiotic activities, which became one of the 'hot' subjects for various biological processes. However, this potential has not been fully explored because the production of oligoesters (e.g. di-, tri- and tetra-) of sugars is a difficult problem in organic chemistry because of the abundance of hydroxyl groups in sugar molecules and the similar reactivity of most of them. Solvent engineering can be employed to improve the yields of sugar esters by using biocatalytic reactions. Protein engineering is useful in improving the catalytic efficiency, thermostability and pH stability of biocatalysts for enzymatic synthesis of sugar ester. The use of recombinant DNA technology to produce large quantities of enzymes in a heterologous host will lower the overall production cost. The cloning of key enzyme genes for the carbohydrate esters biosynthesis pathway and overexpressing these genes using strong promoters in either plants or microorganisms through metabolic engineering will be also discussed in this review.

Inhibition of Rhizomucor miehei and Candida rugosa lipases by d-glucose in esterification between l-alanine and d-glucose

A detailed kinetic study of the esterification of D-glucose with L-alanine catalyzed by lipases from Rhizomucor miehei (RML) and Candida rugosa (CRL) showed that both lipases follow the Ping-Pong Bi-Bi mechanism, in which L-alanine and D-glucose bind in subsequent steps releasing water and L-alanyl-D-glucose, with competitive substrate inhibition by D-glucose at higher concentrations leading to the formation of dead-end lipase.D-glucose complexes. An attempt to obtain the best fit of this kinetic model through curve fitting yielded good approximates of the apparent values of four important kinetic parameters: for RML-k(cat)=0.29+/-0.028x10(-3) M h(-1) mg(-1), K(m L-alanine)= 4.9+/-0.51x10(-3) M, K(m D-glucose)=0.21+/-0.018x10(-3) M, and K(i D-glucose)=1.76+/-0.19x10(-3) M; for CRL-k(cat)= 0.75+/-0.08x10(-3) M h(-1) mg(-1), K(m L-alanine)=56.2+/-5.7x10(-3) M, K(m D-glucose)=16.2+/-1.8x10(-3) M, and K(i D-glucose) =21.0+/-1.9x10(-3) M.