液相色谱法测定生物发酵液中水溶性维生素的研究

本文采用反相离子对色谱测定了生物发酵液中的七种水溶性维生素。提出了用自行装填的酸性氧化铝（０．１９～０．１５ｍｍ）前置柱，和５％乙酸洗脱样品的前处理方法；并就有关的色谱条件进行了选择。色谱柱为ＮｏｖａＰａｋＣ１８；流动相Ａ液为０．０５ｍｏｌ／Ｌ庚烷磺酸盐（ＰＩＣＢ７），冰乙酸调ｐＨ＝２．５；Ｂ液为甲醇＋三乙胺（１００＋０．５）；梯度洗脱；ＵＶ２５４ｎｍ、２９０ｎｍ、３６０ｎｍ同时测定。线性范围为０．１～１０μｇ，各种维生素的ＲＳＤ在１．２％～３．０％之间（ＶｉｔａｍｉｎＢ１２除外），回收率大于９０％。     

Changes in Isoflavone Profile from Soybean Seeds during Cheonggukjang Fermentation Based on High-Resolution UPLC-DAD-QToF/MS: New Succinylated and Phosphorylated Conjugates

In this study, thirty-eight isoflavone derivatives were comprehensively identified and quantified from the raw, steamed and fermented seeds of four selected soybean cultivars based on UPLC-DAD-QToF/MS results with reference to the previously reported LC-MS library and flavonoid database, and summarized by acylated group including glucosides (Glu), malonyl-glucosides (Mal-Glu), acetyl-glucosides (Ac-Glu), succinyl-glucosides (Suc-Glu) and phosphorylated conjugates (Phos) in addition to aglycones. Among them, Suc-Glu and Phos derivatives were newly generated due to fermentation by B. subtilis AFY-2 (cheonggukjang). In particular, Phos were characterized for the first time in fermented soy products using Bacillus species. From a proposed roadmap on isoflavone-based biotransformation, predominant Mal-Glu (77.5–84.2%, raw) decreased rapidly by decarboxylation and deesterification into Ac-Glu and Glu (3.5–8.1% and 50.0–72.2%) during steaming, respectively. As fermentation continued, the increased Glu were mainly succinylated and phosphorylated as well as gradually hydrolyzed into their corresponding aglycones. Thus, Suc-Glu and Phos (17.3–22.4% and 1.5–5.4%, 36 h) determined depending on cultivar type and incubation time, and can be considered as important biomarkers generated during cheonggukjang fermentation. Additionally, the changes of isoflavone profile can be used as a fundamental report in applied microbial science as well as bioavailability research from fermented soy foods.     

Structural Transformation and Stabilization of Metal–Organic Motifs Induced by Halogen Doping

The structural transformation of supramolecular nanostructures with constitutional diversity and adaptability by dynamic coordination chemistry would be of fundamental importance for potential applications in molecular switching devices. The role of halogen doping in the formation of elementary metal–organic motifs on surfaces has not been reported. Now, the 9‐ethylguanine molecule (G) and Ni atom, as a model system, are used for the structural transformation and stabilization of metal–organic motifs induced by iodine doping on Au(111). The iodine atoms are homogeneously located at particular hydrogen‐rich locations enclosed by G molecules by electrostatic interactions, which would be the key for such an unexpected stabilizing effect. The generality and robustness of this approach are demonstrated in different metal–organic systems (G/Fe) and also by chlorine and bromine.     

Transformation of Structure and Properties of Vesicles Induced by Transition Metal Ions

This paper proved that octodecyl propylenediamine could form vesicles in pure water and aqueous solution of CuCl2 or Cu（NO3）2. The structure and morphology of vesicles were different when the copper （Ⅱ） salt was added to the solution. The results showed that both the counterions and the ligands had strong influence on the configuration of coordinated structures and packing model in bilayer membrane of vesicles.     

Structural Transformation of Bovine Serum Albumin Induced by Dimethyl Sulfoxide and Probed by Fluorescence Correlation Spectroscopy and Additional Methods

Determining the structure of a protein and its transformation under different conditions is key to understanding its activity. The structural stability and activity of proteins in aqueous–organic solvent mixtures, which is an intriguing topic of research in biochemistry, is dependent on the nature of the protein and the properties of the medium. Herein, the effect of a commonly used cosolvent, dimethyl sulfoxide (DMSO), on the structure and conformational dynamics of bovine serum albumin (BSA) protein is studied by fluorescence correlation spectroscopy (FCS) measurements on fluorescein isothiocyanate (FITC)‐labeled BSA. The FCS study reveals a change of the hydrodynamic radius of BSA from 3.7 nm in the native state to 7.0 nm in the presence of 40 % DMSO, which suggests complete unfolding of the protein under these conditions. Fluorescence self‐quenching of FITC has been exploited to understand the conformational dynamics of BSA. The time constant of the conformational dynamics of BSA is found to change from 35 μs in its native state to 50 μs as the protein unfolds with increasing DMSO concentration. The FCS results are corroborated by the near‐UV circular dichroism spectra of the protein, which suggest a loss of its tertiary structure with increasing concentration of DMSO. The intrinsic fluorescence of BSA and the fluorescence response of 1‐anilinonaphthalene‐8‐sulfonic acid, used as a probe molecule, provide information that is consistent with the FCS measurements, except that aggregation of BSA is observed in the presence of 40 % DMSO in the ensemble measurements.     

Characterization of Bioactive Compounds from Acacia concinna and Citrus limon,Silver Nanoparticles’ Production by A. concinna Extract,and Their Biological Properties

The applications of bioactive compounds from medicinal plants as therapeutic drugs are largely increasing. The present study selected the bioactive compounds from Acacia concinna (A. concinna) and Citrus limon (C. limon) to assess their phytochemicals, proteins, and biological activity. The plant material was collected, and extraction performed as per the standard procedure. Qualitative analysis was undertaken, and identification of functional organic groups was performed by FTIR and HPLC. Antibacterial, anticancer, antioxidant, antihyperglycemic, antihyperlipidemic, and inhibition kinetics studies for enzymes were performed to assess the different biological activities. Flavonoids and phenols were present in a significant amount in both the selected plants. A. concinna showed significant antimicrobial activity against Z. mobilis, E. coli, and S. aureus, with minimum inhibition zones (MIZ) of 24, 22, and 20 mm, respectively. C. limon strongly inhibited all the tested pathogenic bacteria with maximum and minimum MIZ of 32 and 17 mm. A. concinna silver nanoparticles also exhibited potent antimicrobial activity. Both extracts showed substantial antioxidant, antihyperlipidemic, antidiabetic, anticancer (MCF-7), and anti-urease (antiulcer) properties. To conclude, these plants can be used to treat hyperlipidemia, diabetes, cancer, and gastrointestinal ulcers. They can also serve as antimicrobial and antioxidant agents. Thus, the studied plants must be exploited cost-effectively to generate therapeutic drugs for various diseases.     

Fermentation kinetics of ethanol production from glucose and xylose by recombinant Saccharomyces 1400(pLNH33)

Fermentation kinetics of ethanol production from glucose, xylose, and their mixtures using a recombinant Saccharomyces 1400 (pLNH33) are reported. Single-substrate kinetics indicate that the specific growth rate of the yeast and the specific ethanol productivity on glucose as the substrate was greater than on xylose as a substrate. Ethanol yields from glucose and xylose fermentation were typically 95 and 80% of the theoretical yield, respectively. The effect of ethanol inhibition is more pronounced for xylose fermentation than for glucose fermentation. Studies on glucose-xylose mixtures indicate that the recombinant yeast co-ferments glucose and xylose. Fermentation of a 52.8 g/L glucose and 56.3 g/L xylose mixture gave an ethanol concentration of 47.9 g/L after 36 h. Based on a theoretical yield of 0.51 g ethanol/g sugars, the ethanol yield from this experiment (for data up to 24 h) was calculated to be 0.46 g ethanol/g sugar or 90% of the theoretical yield. The specific growth rate of the yeast on glucose-xylose mixtures was found to lie between the specific growth rate on glucose and the specific growth rate on xylose. Kinetic studies were used to develop a fermentation model incorporating the effects of substrate inhibition, product inhibition, and inoculum size. Good agreements were obtained between model predictions and experimental data from batch fermentation of glucose, xylose, and their mixtures.     

金属-血清蛋白的结构研究Ⅲ.Ni2+离子诱导的HSA和BSA的缓慢构象变化

用紫外光谱观察到Ni2+离子与人或牛血清白蛋白相互作用有显著的滞后效应,表明Ni2+离子的结合可以诱导人或牛血清白蛋白发生从对Ni2+离子有较弱亲和力至较强亲和力构象态的缓慢变化(T-R转化);这一构象变化为试样的旋光能力随时间变化进一步证实;测得并讨论了这一构象变化的速度常数和活化参数;推测这一构象变化可能主要发生在蛋白质的IA亚区,并且很可能是一种促使IA亚区变得更加开放的"绞链式运动".     

Structural and Biological Properties of Vermistatin and Two New Vermistatin Derivatives Isolated from the Marine‐Mangrove Endophytic Fungus Guignardia sp. No. 4382

Vermistatin (=(3R)‐4,6‐dimethoxy‐3‐{4‐oxo‐6‐[(1E)‐prop‐1‐en‐1‐yl]‐4H‐pyran‐3‐yl}‐2‐benzofuran‐1(3H)‐one; 1 ) and two new vermistatin derivatives, compounds 2 and 3 , were isolated from the fungal strain Guignardia sp. No. 4382 obtained from the South‐China Sea. Their structures were elucidated by various methods, including circular dichroism (CD), 1D‐ and 2D‐NMR, and HR‐EI‐MS. The structures of 1 and 2 were unequivocally corroborated by X‐ray crystallography, and their absolute configurations were derived by CD spectroscopy based on a literature comparison. The in vitro cytotoxic and antifungal activities of 1 and 2 were tested.