Michel Pina

Esterification of phenolic acids from green coffee with an immobilized lipase from Candida antarctica in solvent-free medium

Phenolic acid esters were synthesized by direct esterification catalysed by an immobilized lipase obtained from Candida antarctica. Esterification yields ranged from 3 to 98%; yields seem to be linked to the electronic distribution of phenolic acids which affects the reactivity of the carboxylic function. The carbon chain length of the alcohols also plays an important role. It was observed that even for high yields, reaction times were two days or more.

Fructose oleate synthesis in a fixed catalyst bed reactor

SummaryFructose oleate undergoes continuous synthesis in a fixed catalyst bed reactor using an industrial fixed lipase. The effects of the time spent in the reactor, substrate concentration and effluent recycling are studied. A yield of 83% is obtained by recycling the effluent 3 times.

Effect of water activity on enzymatic synthesis of alkylglycosides

Water activity (aw) was studied during biocatalyzed alkylglycoside synthesis using defated raw almond meal displaying a good β glucosidasic activity. Optimum aw were determined for several alcohols used for the alkylation of the sugar. Above and below optimum aw, yield decreased rapidly.

Quantitative and qualitative study of gastric lipolysis in premature infants : Do MCT-enriched infant formulas improve fat digestion?

Intragastric fat digestion was investigated by analyzing the products of lipolysis and the gastric lipase (HGL) levels of premature infants fed with a formula enriched with medium chain triglycerides (MCT) and those of infants fed with human milk. Infants were fed using a gastric tube and the gastric contents were aspirated twice a day for 5 d, before and at various times after gavage feeding. HGL levels were measured using the pHstat technique. After extraction, lipids were separated and quantified using thin-layer chromatography coupled to a flame ionization detector. Fatty acid methyl esters were analyzed by gas chromatography. HGL concentration increased during digestion, reaching 77.4 ± 43.1 μg/mL (around 75% of those recorded in adults). Mean HGL output was 115 ± 43 μg for 3 h and the overall intragastric lipolysis was 6.1 ± 2.6%. Although the formula was enriched with octanoic and decanoic acid, the main fatty acids released in the stomach were palmitic (C16:0, 17.03 ± 0.23% wt/wt) and oleic (C18:1 n-9, 28.23 ± 1.26% wt/wt) acid. Similar results were obtained with infants fed with human milk. MCT supplementation has no quantitative or qualitative effects on the intragastric lipolysis, which is not higher in premature infant than in adults.

Carica papaya latex lipase : sn-3 stereoselectivity or short-chain selectivity ? Model chiral triglycerides are removing the ambiguity

Short-chain fatty acids are usually located at positionsn-3 in natural triglycerides, particulary in dairy fats. As a result, it is extremely difficult to differentiate betweensn-3 stereospecificity and short-chain typoselectivity in many lipases and acyltransferases that perform in this way. This ambiguity can be removed through successive use of a chiral triglyceride with a short fatty acid in positionsn-1 and of its racemic in controlled hydrolysis reactions. After checking that the proposed method effectively confirmed the type of activity of control biocatalysts (Candida cylindracea nonspecific lipase andMucor miehei 1–3 regiospecific lipase), we confirmed thatCarica papaya latex has a strictsn-3 stereospecificity.

Purification and properties of the lipase fromCandida deformans (zach) langeron and guerra

Palm oil being solid at room temperature could be converted into a fluid oil by substitution of about 40–50% of its palmitic acid. This could be achieved by a fermentation process or using yeast lipase.Candida deformans CBS 2071 seemed suitable for this purpose: therefore, its lipase was isolated and studied. This enzyme was purified by acetone precipitation followed by chromatographies on Sephadex C 50 and Sephadex G 150. The purification factor achieved was ×70, and the protein and activity yields were 0.25% and 18%, respectively. The homogeneity of the purified enzyme was verified by polyacrylamide gel electrophoresis. The enzyme molecular weight was estimated at 207,000. Its activity is optimal between 40 C and 50 C and its optimum pH is 7.0. This enzyme is thermo-resistant and loses only 14% and 18% of its activity, respectively, when heated to 45 C and 55 C for 30 min. Its activation energy was 2.75 kcal.mole−1 and its inactivation energy was around 21 kcal.mole−1. This enzyme is activated by Ca++, Mg++ and Co++ and inhibited by Cu++, Zn++, and p-chloromercuribenzoate (pCMB) and EDTA.The synthesis of this lipase is induced by lipid substrates in the culture medium and inhibited by glucose. This enzyme attacks primarily the 1- (or 3-) position of all triglycerides tested. Hydrolysis was preferential for triglycerides containing short chain fatty acids. The triglycerides with monounsaturated monoacids were more quickly hydrolyzed, than those with saturated monoacids. The presence of two and especially three double bonds in the fatty acid chain seemed to slow down the rate of hydrolysis.

Identification and biochemical characterization of a GDSL-motif carboxylester hydrolase from Carica papaya latex.

An esterase (CpEst) showing high specific activities on tributyrin and short chain vinyl esters was obtained from Carica papaya latex after an extraction step with zwitterionic detergent and sonication, followed by gel filtration chromatography. Although the protein could not be purified to complete homogeneity due to its presence in high molecular mass aggregates, a major protein band with an apparent molecular mass of 41 kDa was obtained by SDS-PAGE. This material was digested with trypsin and the amino acid sequences of the tryptic peptides were determined by LC/ESI/MS/MS. These sequences were used to identify a partial cDNA (679 bp) from expressed sequence tags (ESTs) of C. papaya. Based upon EST sequences, a full-length gene was identified in the genome of C. papaya, with an open reading frame of 1029 bp encoding a protein of 343 amino acid residues, with a theoretical molecular mass of 38 kDa. From sequence analysis, CpEst was identified as a GDSL-motif carboxylester hydrolase belonging to the SGNH protein family and four potential N-glycosylation sites were identified. The putative catalytic triad was localised (Ser(35)-Asp(307)-His(310)) with the nucleophile serine being part of the GDSL-motif. A 3D-model of CpEst was built from known X-ray structures and sequence alignments and the catalytic triad was found to be exposed at the surface of the molecule, thus confirming the results of CpEst inhibition by tetrahydrolipstatin suggesting a direct accessibility of the inhibitor to the active site.

A study of the influence of the growth media on the fatty acid composition in Candida lipolytica Diddens and Lodder

Candida lipolytica YB 423-12 is able to incorporate fatty acid from the culture medium when lipids are used as carbon substrate. The composition of cell lipids is largely dependent on that of the culture medium. An important Δ 9 desaturase activity acts on incorporated palmitic and stearic acids; and Δ 11-eicosenoic and erucic acids are shortened to oleic acid.

Specificity of #Carica papaya# latex in lipase-catalyzed interesterification reactions

Enzymatic interesterification of the chiral triacylglycerol, 1-butyroyl-2-stearoyl-3-palmitoyl-sn-glycerol (sn-BSP) with trimyristin indicated that the lipase present in Carica papaya latex exhibits an sn3 stereoselectivity. Other interesterification experiments with homogeneous triacylglycerols of varying chain length with tricaprylin showed that this enzyme also has a typoselectivity for short chain fatty acids.

Enzymatic synthesis of N-ε-acyllysines

Chemical synthesis of N-ε-acyllysines on an industrial scale corresponds to new requirements in the surfactant field; only one chemical synthesis process is currently known for this type of molecule. A number of organic synthesis conducted in the laboratory so far have not made it possible to consider industrial development. However, biotechnologically, it has been shown that this molecule is easily accessible using a commercially available fixed lipase. Synthesis is carried out by causing a triglyceride to react with the lysine either with or without a solvent. The latter method gives the best results at the current stage of research. Given the availability of at least one fixed lipase on the market today, and the possibility of directly applying the reaction using oils, this reaction could be scaled up rapidly for industrial development.