PubMed · 17051634
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Nicolas Delsuc, Jean-Michel Léger, Stéphane Massip, Ivan Huc. 2007. Proteomorphous objects from abiotic backbones.. https://doi.org/10.1002/anie.200603390
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An environmentally benign and volume efficient process for enzymatic production of alkanolamides is described. Immobilized Candida antarctica lipase B, Novozym435, was used to catalyze the condensation of lauric acid with monoethanolamine. The reaction temperature of 90 degrees C was required to keep the reactants in a liquid state. Stepwise addition of the amine minimized problems caused by the formation of a highly viscous amine/fatty acid ion-pair. The enzyme was both very active and stable under the reaction conditions, with about half of the activity remaining after 2 weeks. The maximum amide yield obtained when using equimolar amounts of the reactants was 75%, which could be increased to 95% upon water removal. Special precautions to avoid co-distillation of the amine were required. Two different strategies to avoid the amine loss are presented.
Expression of functionally active thrombomodulin (TM) on the luminal surface of endothelial cells is critical for vascular thromboresistance. The 3-hydroxyl-3-methyl coenzyme A reductase inhibitor, pravastatin, can protect the vasculature in a manner that is independent of its lipid-lowering activity. We examined the effect of pravastatin on TM expression by human aortic endothelial cells (HAECs) with subsequent tumor necrosis factor alpha (TNFalpha) stimulation and investigated the signaling pathways involved. TNFalpha treatment attenuated TM expression in HAECs in a time-dependent manner. Pravastatin upregulated TM levels in TNFalpha-treated HAECs. Specific inhibition of geranylgeranyltransferase-I or the Rho family by GGTI-286 or TcdB, respectively, enhanced TM expression in TNFalpha-treated HAECs, whereas MAP kinase inhibitors, inactivation of Rho by Clostridium botulinum C3 exoenzyme, or the Rho kinase inhibitor, Y-27632, had no effect. In TNFalpha-treated HAECs, pravastatin inhibited Rac1 and Cdc42 activation and their translocation to the cell membrane. Blocking the transcriptional activation of NF-kappaB prevented the TNFalpha-induced downregulation of TM. The pravastatin-induced increase in TM expression in TNFalpha-treated HAECs was mediated through inhibition of NF-kappaB activation. Pravastatin regulates TM expression by inhibiting the activation of the Rho family proteins, Rac1 and Cdc42, and the transcription factor, NF-kappaB. The increase in endothelial TM activity in response to pravastatin constitutes a novel pleiotropic (nonlipid-related) effect of this commonly used compound and may be of clinical significance in disorders in which deficient endothelial TM plays a pathophysiological role.
Different deamidation conditions for the Z19 alpha-zein were studied in order to find the best conditions for the development of the emulsifying properties. Alkaline deamidation was chosen, and the effects on the peptide bond cleavage, secondary structure, emulsifying properties, and surface hydrophobicity were studied. The Z19 alpha-zein was deamidated by using 0.5 N NaOH containing 70% ethanol at 70 degrees C for 12 h. A deamidation degree (DD) of 60.6 +/- 0.5%, and a degree of hydrolysis (DH) of 5 +/- 0.5% were achieved. Analysis by far-UV circular dichroism showed that the denaturation was mainly promoted by the high temperature used during the incubation. The adequate balance between the DD and the DH results in an effective emulsifying property improvement for the Z19 alpha-zein. Thus, after the deamidation treatment, the surface hydrophobicity decreased from 9.5 x 104 +/- 6.8 x 103 to 46 x 104 +/- 2.1 x 103, and the emulsion stability increased from 18 +/- 0.7% to 80 +/- 4.7% since the oil globules stabilized by the modified protein were smaller (57.7 +/- 5.73 nm) and more resistant to coalescence than those present in the native protein emulsions (1488 +/- 3.92 nm).