Promotion of a lipase-catalyzed esterification in supercritical carbon dioxide in the near-critical region
β Scribed by Y. Ikushima; N. Saito; K. Hatakeda; O. Sato
- Publisher
- Elsevier Science
- Year
- 1996
- Tongue
- English
- Weight
- 467 KB
- Volume
- 51
- Category
- Article
- ISSN
- 0009-2509
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β¦ Synopsis
The ester syntheses from acyl donors and terpene alcohols catalyzed by Candida cylindracea(CCL) lipase have been carried out in supercritical carbon dioxide(SC-CO2). In the nearcritical region, the rate of esterification showed a sharp maximum and /-terpene esters were stereoselectively synthesized from acyl donors and a primary alcohol such as (d/)-citronellol. It was found that, in very limited pressure range near the critical point, the interactions between carbon dioxide and enzyme molecules are greatly increased and allowed to provoke drastic conformational changes of the enzyme, causing active sites to emerge and catalyze the stereoselective syntheses. Supercritical carbon dioxide medium in the near-critical region should be a trigger to the activation of the enzyme by causing the movement of the surface groups and creating an active site, producing stereoselective machinery.
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## Abstract The stability and activity of lipases from __Pseudomonas fluorescens, Rhizopus javanicus, Rhizopus niveus__, porcine pancreas and __Candida rugosa__ in a nonβsolvent system at atmospheric pressure, in supercritical carbon dioxide (SCβCO~2~), and nearβcritical propane at 100 bar and 40βΒ°
Flow calorimetric measurements of the excess molar enthalpy H E m for {xCO 2 + (1 -x) C 2 H 4 } are described. The measurements cover the range T = 260.95 K to T = 315.75 K at pressures from 3.5 MPa to 12.6 MPa. Liquid phase measurements were made at the pressure 11.0 MPa over the range T = 260.95 t