New synthesis of 6[3-(1-adamantyl)-4-methoxyphenyl]-2-naphthoic acid and evaluation of the influence of adamantyl group on the DNA binding of a naphthoic retinoid

6[3-(1-Adamantyl)-4-methoxyphenyl]-2-naphthoic acid (Adapalene®), a synthetic aromatic retinoid specific for RARβ and RARγ receptors, has been prepared utilizing a Pd/C-mediated Suzuki coupling between 6-bromo-2-naphthoic acid and 4-methoxyphenyl boronic acid, followed by introduction of an adamantyl group in the position 3 of the formed 6-(4-methoxyphenyl)-2-naphthoic acid. The interaction of 6-(4-methoxyphenyl)-2-naphthoic acid/ethyl ester and the 3-adamantyl analogs with DNA was studied in aqueous solution at physiological conditions by UV–vis spectroscopy. The calculated binding constants K_ligand–DNA ranged between 1.1 × 10⁴ M⁻¹ and 1.1 × 10⁵ M⁻¹, the higher values corresponding to those of the adamantylated compounds. Molecular modeling studies have emphasized that the intercalative binding of adapalene and its derivatives to DNA is mainly stabilized by hydrophobic interactions related to the presence of the adamantyl group.     

Simple and efficient immobilization of lipase B from Candida antarctica on porous styrene-divinylbenzene beads

Two commercial porous styrene-divinylbenzene beads (Diaion HP20LX and MCI GEL CHP20P) have been evaluated as supports to immobilize lipase B from Candida antarctica (CALB). MCI GEL CHP20P rapidly immobilized the enzyme, permitting a very high loading capacity: around 110 mg CALB/wet g of support compared to the 50 mg obtained using decaoctyl Sepabeads. Although enzyme specificity of the enzyme immobilized on different supports was quite altered by the support used in the immobilization, specific activity of the enzyme immobilized on MCI GEL CHP20P was always higher than those found using decaoctyl Sepabeads for all assayed substrates. Thus, a CALB biocatalyst having 3-8 folds (depending on the substrate) higher activity/wet gram of support than the commercial Novozym 435 was obtained. Half-live of CAL-Diaion HP20LX at 60 °C was 2-3 higher than the one of Novozym 435, it was 30-40 higher in the presence of 50% acetonitrile and it was around 100 folds greater in the presence of 10 M hydrogen peroxide.Results indicate that styrene-divinylbenzene supports may be promising alternatives as supports to immobilize CALB.     

Influence of sodium chloride on hydrophobic adsorption of PEGylated lysozyme

Interaction of macromolecules in aqueous salt‐containing solution with a hydrophobic adsorbent is studied by adsorption equilibrium measurements and by independent isothermal titration calorimetry. The macromolecules are native as well as mono‐, di‐, and tri‐PEGylated lysozyme and four pure PEGs. The hydrophobic adsorbent is Toyopearl PPG‐600M. The salt is sodium chloride. The sodium chloride concentration in the aqueous 25 mM sodium phosphate buffer is varied from 2000 to 4500 mM at pH 7.0 and 25°C. PEGylation of the lysozyme is carried using 5 and 10 kDa PEG chains. The molar enthalpy of adsorption is calculated from the adsorption equilibrium and the calorimetric data. The results show that the adsorption of the PEGylated lysozyme is caused by both the interaction of the lysozyme and the interaction of the PEG chains with the adsorbent, respectively, but the interaction of the lysozyme is stronger than that of PEG. The comparison of the results of the present study on the influence of sodium chloride with a corresponding study on the influence of ammonium sulfate shows that the adsorption mechanism changes upon the variation of the salt. The knowledge of the adsorption mechanisms supports the systematic development of chromatographic purification steps.     

Structural and functional characterization of polyethylene terephthalate hydrolase from Ideonella sakaiensis

Polyethylene terephthalate (PET) hydrolase from Ideonella sakaiensis (IsPETase) can be used to degrade PET. In order to use IsPETase in industry, we studied the enzymatic activity of IsPETase in different conditions containing environmental and physicochemical factors commonly found in nature. We observed that salts and glycerol enhanced the enzymatic activity, while detergents and organic solvents reduced the enzymatic activity. IsPETase hydrolyzed p-nitrophenyl (p-NP) esters instead of naphthyl esters. To make IsPETase an enzyme capable of hydrolyzing naphthyl esters, site-directed mutagenesis was carried out based on the structural information provided by the crystal structure. We found that the IsPETase^S93M, IsPETase^W159F, and IsPETase^N241F mutants can hydrolyze naphthyl esters. IsPETase engineering can direct researchers to use this α/β-hydrolase protein scaffold to design enzymes that can hydrolyze a variety of polyesters.     

Rationalization of poor solubility of TGF-β3 using MD simulation

Despite sequence and structural similarity, TGF-β3 has low solubility among other isoforms of TGF-β. We used nanosecond of molecular dynamic simulations (MD) with explicit solvent, alone and in presence of urea, to investigate the intermediates resulting from the unfolding process of TGF-β3 and TGF-β1. MD simulations of the full-length proteins show a very early loss of α-helix in TGF-β3 compared to the one in the TGF-β1. MD simulation of a small fragment consisting of H3 α-helix of TGF-β3 shows conversion of this segment to β-sheet. Relative instability of H3 α-helix in TGF-β3 and its propensity to form β-sheet may explain the poor solubility of TGF-β3 compared to TGF-β1. The other reasons for poor solubility of TGF-β3 may be the hydrophobic patches on its surface and low charge over the entire range of pH.     

两相系统在疏水性有机污染物高效降解菌富集培养中的应用研究进展

环境中疏水性有机污染物(Hydrophobic organic pollutants,HOPs)的浓度日益增加,获取HOPs高效降解功能微生物能有效提高HOPs污染治理效率。近年来,利用两相系统促进HOPs微生物降解转化的研究已取得一定进展。本文重点从两相系统的结构特点及其富集HOPs降解功能微生物的原理、主要影响因素和应用情况等方面进行综述,并在此基础上对两相系统在毒害性HOPs微生物加速降解脱毒中所存在的主要问题及其应用前景进行讨论和展望。     

Membrane order perturbation in the presence of antimicrobial peptides by H solid-state NMR spectroscopy

The ²H solid-state NMR spectra of deuterated fatty acyl chains provide direct access to the order of the hydrophobic membrane interior. From the deuterium order parameter profiles of perdeuterated fatty acyl chains the membrane hydrophobic thickness can be calculated. Here we show data obtained from POPC, POPE and mixed POPE/POPG bilayers, representative of bacterial membranes, in the presence of cholesterol or ergosterol and antimicrobial peptaibols. Whereas sterols have a strong ordering effect also on these membranes, the peptides exhibit neutral or disordering effects. By comparing with data from the literature it becomes obvious that cationic amphipathic peptides that probably reside within the interface of phospholipid membranes tend to strongly disorder the packing of the fatty acyl chains, an effect that has been correlated to antimicrobial and DNA transfection activities. In contrast transmembrane sequences or hydrophobic peptides that probably partition deeply into the membrane tend to have only modest disordering activities. The ²H solid-state NMR approach has also been used to monitor the lateral separation of domains rich in anionic phospholipids in the presence of cationic peptides and has thereby provided important insights into their mechanisms of action.     

疏水吸附法稳定糖化酶的研究

 本文提出了一种新的稳定糖化酶的方法。用带有疏水基团的亲水性多糖,可以方便有效地稳定糖化酶,明显提高了糖化酶的储存稳定性。实验结果表明,在含有芳香基右旋糖酐,钙离子,甘油的缓冲溶液中,糖化酶于室温放置5个月,酶活力没有损失,放置7个月,活力只损失15.7％。