《孔雀东南飞》质疑

笔者在讲解与北朝《木兰诗》并称“乐府双璧”的南朝乐府民歌《孔雀东南飞》时，不论是备课前还是上课后，始终有几个疑点在脑海中回旋，一是兰芝从初来到驱遣，小姑的年龄问题；二是兰芝被遣回家后，先后到底有几家来提亲的问题。

Equilibrium Studies on Liquid-Liquid Reactive Extraction of Phenylsuccinic Acid Enantiomers Using Hydrophilicβ-CD Derivatives Extractants

This paper deals with the enantioseparation of phenylsuccinic acid(H2A)enantiomers by liquid-liquid reactive extraction usingβ-CD derivatives as aqueous selectors.Cyclodextrin and its derivatives can interact with guest molecules selectively to form complexes with different stabilities.Cyclodextrin derivatives are not soluble in organic liquids,but highly soluble in water.In this work,hydroxypropyl-β-cyclodextrin(HP-β-CD),hydroxyethyl- β-cyclodextrin(HE-β-CD)and methyl-β-cyclodextrin(Me-β-CD)were selected as chiral selectors in aqueous phase for the reactive extraction of phenylsuccinic acid enantiomers from organic phase to aqueous phase.The results show that the efficiency of the extraction depends,often strongly,on a number of process variables,including the types of organic solvents andβ-CD derivatives,the concentrations of the extractants and H2A enantiomers,pH and temperature.HP-β-CD,HE-β-CD and Me-β-CD have stronger recognition abilities for R-phenylsuccinic acid than for S-phenylsuccinic acid.Among the three kinds ofβ-CD derivatives,HP-β-CD has the strongest separation ability. Excellent enantioseparation was achieved under the optimal conditions of pH of 2.5 and temperature of 5°C with a maximum enantioselectivity(a)of 2.38.Reactive extraction of enantiomers with hydrophilicβ-CD derivatives is of strong chiral separation ability and can be hopeful for separations of various enantiomers at a large-scale.

The effects of DNA intercalators on chromatin of chicken red blood cells---differential extraction on nonhistone proteins

Taking advantage of the effects on DNA secondary structure of two DNA-intercalators,ethidium bromide and chloroquine,we used each of them to treat nuclei from both mature erythrocytes and reticulocytes of chicken,as an alternative approach to study the relationships between DNA secondary structure,nuclear proteins and chromatin structure.We presented results of differential extraction of nuclear proteins from nuclei with DNA-intercalators,as well as preliminary characterization of these proteins.A 45kd protein is the major component in fractions extracted by both intercalators from nuclei from either mature erythrocytes or reticulocytes and seems to be a DNA-binding protein.Furthermore,from current concepts of functional aspects of DNA conformation and structural heterogeneity in chromatin and nuclear proteins,we have discussed both the significance of our results as well as technical aspects of this approach.

Affinity Purification of Insulin by Peptide-Ligand Affinity Chromatography

The affinity heptapeptide(HWWWPAS)for insulin,selected from phage display library,was coupled to EAH Sepharose 4B gel and packed to a 1-mL column.The column was used for the affinity purification of insulin from protein mixture and commercial insulin preparation.It was observed that the minor impurity in the commercial insulin was removed by the affinity chromatography.Nearly 40 mg of insulin could be purified with the 1-mL affinity column.The results revealed the high specificity and capacity of the affinity column for insulin purification.Moreover,based on the analysis of the amino acids in the peptide sequence,shorter peptides were designed and synthesized for insulin chromatography.As a result,HWWPS was found to be a good alternative to HWWWPAS,while the other two peptides with three or four amino acids showed weak affinity for insulin.The results indicated that the peptide sequence of HWWWPAS was quite conservative for specific binding of insulin.

OPTIMIZATIONOFTHECONTINUOUSAFFINITY－RECYCLEEXTRACTIONPROCESS

Single step and multi step CARE processes are optimized by computer simulations based on the mathematical model proposed previously. The product of purification factor and recovery yield is used as the objective function for optimizing a single step process. The objective function for the optimization of a multi step process is considered to obtain an anticipated product purity at a maximum recovery yield and a minimum number of CARE inividuals. Pairs of the operating conditions (eluant and affinity recycle flow rates) exist to give the maximums of above objective functions when membrane rejections to ligates and contaminants are equal in value. The optimum affinity recycle flow rate decreases with the increase of membrane rejections and equilibrium binding fractions of ligates. For a multi step process, when contaminants are rejected less than ligate, only one pair of the optimum eluant and affinity recycle flow rates exists.

PERFORMANCE OF THE CONTINUOUS AFFINITY-RECYCLE EXTRACTION PROCESS

The continuous affinity- recycle extraction (CARE) process is extended ic a system with ultrafiltration membranes. The mathematical model of the process is established by taking into account membrane rejections to the components in a crude mixture. The process performance, defined as concentration factor (CF ), purification factor (PF ) and recovery yield (REC), is analyzed by computer simulations. The results show that CF and REC increase, but PF decreases with the membrane rejection. It is likely that optimum operating conditions exist to give the best process performance because the increases in eluant and affinity-recycle flow rate improve REC but decrease PF.

Bee Pollen in Transylvania （Romania）： Palynological Characterization and ORACFL Values of Lipophilic and Hydrophilic Extracts of Monofloral Pollen Pellets

A melissopalynological study carried out on 35 bee pollen samples from Romania （Transylvania） shows predominant species as Taraxacum officinale, Tilia sp., Ferbascum sp., Zea mays L., Onobrychis viciifolia Scop., Geranium sanguineum L., Filipendula ulmaria L., Cydonia oblonga L., Calluna vulgaris L. and Brassica sp.. This is the first time for the contribution of total phenolic （TP） and total carotenoid （TC） content to the modified oxygen radical absorbance capacity （ORACFL） values in 29 monofloral samples. Hydrophilic ORACFL （H-ORACFL） values ranged between 7.13-10.12 μmol TE/g and 6.94-22.46 μmol TE/g, whereas lipophilic ORACFL （L-ORACFL）values were between 2.19-7.79 μmol TE/g and 1.65-9.96 μmol TE/g, in multifloral and monofloral samples, respectively. It has proved the complex involvement of botanical origins on the antioxidant features with a specific occurrence. Some monofloral samples presented particular high antioxidant potential, such as Salix sp., Taraxacum officinale, Matricaria chamomilla, Cichorium intybus and the poorly studied Cirsium arvense （L.） Scop. and Scilla bifolia L.. New variables, such as soil characteristics, climates together with botanical origins, were introduced in a multivariate analysis of antioxidant data matrix, given a possible important involvement of all of them in affecting, not only the phytochemical composition, but thereafter the antioxidant capacity. All these data could be crucial to a new way of gathering, by beekeepers, depending on the market demand and the purposes for the product that has a potential for further therapeutic bioactivities investigations, and added value in the enrichment of certain products.

Structural analysis of a nanoparticle containing a lipid bilayer used for detergent-free extraction of membrane proteins

In the past few years there has been a growth in the use of nanoparticles for stabilizing lipid membranes that contain embedded proteins. These bionanoparticles provide a solution to the challenging problem of membrane protein isolation by maintaining a lipid bilayer essential to protein integrity and activity. We have previously described the use of an amphipathic polymer （poly（styrene-co-maleic add）, SMA） to produce discoidal nanoparticles with a lipid bilayer core containing the embedded protein. However the structure of the nanoparticle itself has not yet been determined. This leaves a major gap in understanding how the SMA stabilizes the encapsulated bilayer and how the bilayer relates physically and structurally to an unencapsulated lipid bilayer. In this paper we address this issue by describing the structure of the SMA lipid particle （SMALP） using data from small angle neutron scattering （SANS）, electron microscopy （EM）, attenuated total reflection Fourier transform infrared spectroscopy （ATR-FTIR）, differential scanning calorimetry （DSC） and nuclear magnetic resonance spectroscopy （NMR）. We show that the particle is disc shaped containing a polymer ＂bracelet＂ encircling the lipid bilayer. The structure and orientation of the individual components within the bilayer and polymer are determined showing that styrene moieties within SMA intercalate between the lipid acyl chains. The dimensions of the encapsulated bilayer are also determined and match those measured for a natural membrane. Taken together, the description of the structure of the SMALP forms the foundation for future development and applications of SMALPs in membrane protein production and analysis.