- Structure and function of bile. I. Relation between the structure of artificial bile and activity of pancreatic lipase
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An aqueous solution of lecithin, bile salts, and cholesterol (artificial bile) which resembles human bile was studied by means of polarizing microscopy, electron microscopy, spin-probe electron spin resonance (ESR) spectroscopy, and pancreatic lipase treatment to digest fatty esters. The relation between the structure of artificial bile and the digestion of fatty esters by pancreatic lipase was investigated, and the following results were obtained. Artificial bile consists of bile salt micelles and bile salt-lecithin-cholesterol mixed micelles. Fatty esters are solubilized in these micelles. Lipase hydrolyzes fatty esters solubilized in bile salt micelles but not in bile salt-lecithin-cholesterol mixed micelles. Ranging from 0.1 to 0.4 μ in size, the macromolecular complex of bile salt-lecithin-cholesterol can be observed by electron microscopy.
- Uematsu,Unno,Niikura,Sawaumi,Akahori
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- Alteration of Chain Length Selectivity of Candida antarctica Lipase A by Semi-Rational Design for the Enrichment of Erucic and Gondoic Fatty Acids
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Biotechnological strategies using renewable materials as starting substrates are a promising alternative to traditional oleochemical processes for the isolation of different fatty acids. Among them, long chain mono-unsaturated fatty acids are especially interesting in industrial lipid modification, since they are precursors of several economically relevant products, including detergents, plastics and lubricants. Therefore, the aim of this study was to develop an enzymatic method in order to increase the percentage of long chain mono-unsaturated fatty acids from Camelina and Crambe oil ethyl ester derivatives, by using selective lipases. Specifically, the focus was on the enrichment of gondoic (C20:1 cisΔ11) and erucic acid (C22:1 cisΔ13) from Camelina and Crambe oil derivatives, respectively. The pursuit of this goal entailed several steps, including: (i) the choice of a suitable lipase scaffold to serve as a protein engineering template (Candida antarctica lipase A); (ii) the identification of potential amino acid targets to disrupt the binding tunnel at the adequate location; (iii) the design, creation and high-throughput screening of lipase mutant libraries; (iv) the study of the selectivity towards different chain length p-nitrophenyl fatty acid esters of the best hits found, as well as the analysis of the contribution of each amino acid change and the outcome of combining several of the aforementioned residue alterations and, finally, (v) the selection and application of the most promising candidates for the fatty acid enrichment biocatalysis. As a result, enrichment of C22:1 from Crambe ethyl esters was achieved either, in the free fatty acid fraction (wt, 78%) or in the esterified fraction (variants V1, 77%; V9, 78% and V19, 74%). Concerning the enrichment of C20:1 when Camelina oil ethyl esters were used as substrate, the best variant was the single mutant V290W, which doubled its content in the esterified fraction from approximately 15% to 34%. A moderately lower increase was achieved by V9 and its two derived triple mutant variants V19 and V20 (27%). (Figure presented.).
- Zorn, Katja,Oroz-Guinea, Isabel,Brundiek, Henrike,D?rr, Mark,Bornscheuer, Uwe T.
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p. 4115 - 4131
(2018/10/02)
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- Stabilization of polynucleotide complexes
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Polynucleotide complexes are stabilized by adding a cryoprotectant compound and lyophilizing the resulting formulation. The lyophilized formulations are milled or sieved into a dry powder formulation which may be used to deliver the polynucleotide complex. Delivery of the polynucleotide to a desired cell tissue is accomplished by contacting the tissue with the powder to rehydrate it. In a preferred embodiment, a dry powder formulation is used to induce genetic modification of a patient's lung tissue.
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