共查询到20条相似文献,搜索用时 15 毫秒
1.
Douglas B. Jordan J. Rose Stoller Charles C. Lee Victor J. Chan Kurt Wagschal 《Applied biochemistry and biotechnology》2017,181(1):250-266
Cartilage tissue engineering is believed to provide effective cartilage repair post-injuries or diseases. Biomedical materials play a key role in achieving successful culture and fabrication of cartilage. The physical properties of a chitosan/gelatin hybrid hydrogel scaffold make it an ideal cartilage biomimetic material. In this study, a chitosan/gelatin hybrid hydrogel was chosen to fabricate a tissue-engineered cartilage in vitro by inoculating human adipose-derived stem cells (ADSCs) at both dynamic and traditional static culture conditions. A bioreactor that provides a dynamic culture condition has received greater applications in tissue engineering due to its optimal mass transfer efficiency and its ability to simulate an equivalent physical environment compared to human body. In this study, prior to cell-scaffold fabrication experiment, mathematical simulations were confirmed with a mass transfer of glucose and TGF-β2 both in rotating wall vessel bioreactor (RWVB) and static culture conditions in early stage of culture via computational fluid dynamic (CFD) method. To further investigate the feasibility of the mass transfer efficiency of the bioreactor, this RWVB was adopted to fabricate three-dimensional cell-hydrogel cartilage constructs in a dynamic environment. The results showed that the mass transfer efficiency of RWVB was faster in achieving a final equilibrium compared to culture in static culture conditions. ADSCs culturing in RWVB expanded three times more compared to that in static condition over 10 days. Induced cell cultivation in a dynamic RWVB showed extensive expression of extracellular matrix, while the cell distribution was found much more uniformly distributing with full infiltration of extracellular matrix inside the porous scaffold. The increased mass transfer efficiency of glucose and TGF-β2 from RWVB promoted cellular proliferation and chondrogenic differentiation of ADSCs inside chitosan/gelatin hybrid hydrogel scaffolds. The improved mass transfer also accelerated a dynamic fabrication of cell-hydrogel constructs, providing an alternative method in tissue engineering cartilage. 相似文献
2.
Bruno Benoliel Marcio José Poças-Fonseca Fernando Araripe Gonçalves Torres Lidia Maria Pepe de Moraes 《Applied biochemistry and biotechnology》2010,160(7):2036-2044
A β-glucosidase gene (bgl4) from Humicola grisea var thermoidea was successfully expressed in Saccharomyces cerevisiae. The recombinant protein (BGL4
Sc
) was initially detected associated with yeast cells and later in the culture medium. BGL4
Sc
showed optimal pH and temperature of 6.0 and 40 °C, respectively, and an apparent molecular mass of 57 kDa. The enzyme showed
activity against cellobiose and synthetic substrates, and was inhibited more than 80% by Fe2+, Cu2+, Zn2+, and Al3+. Using p-nitrophenyl-β-d-glucopyranoside (pNPG) as substrate, BGL4
Sc
presented a V
max of 6.72 μmol min−1 mg total protein−1 and a K
m of 0.16 mM under optimal conditions. Most important, BGL4
Sc
is resistant to inhibition by glucose and the calculated K
i value for this sugar is 70 mM. This feature prompts BLG4
Sc
as an ideal enzyme to be used in the saccharification process of lignocellulosic materials for ethanol production. 相似文献
3.
Background
Since chitin is a highly abundant natural biopolymer, many attempts have been made to convert this insoluble polysaccharide into commercially valuable products using chitinases and β-N-acetylglucosaminidases (GlcNAcases). We have previously reported the structure and function of chitinase A from Vibrio harveyi 650. This study t reports the identification of two GlcNAcases from the same organism and their detailed functional characterization. 相似文献4.
Toshima Omori Keiji Ueno Kei Muramatsu Masanori Kikuchi Shuichi Onodera Norio Shiomi 《Chemistry Central journal》2010,4(1):9
Background
We have previously reported on purification and characterization of β-fructofuranosidase (β-FFase) from Bifidobacterium adolescentis G1. This enzyme showed high activity of hydrolysis on fructo-oligosaccharides with a low degree of polymerization. Recently, genome sequences of B. longum NCC2705 and B. adolescentis ATCC 15703 were determined, and cscA gene in the both genome sequences encoding β-FFase was predicted. Here, cloning of cscA gene encoding putative β-FFase from B. adolescentis G1, its expression in E. coli and properties of the recombinant protein are described. 相似文献5.
Jiayun Qiao Zhenghua Rao Bing Dong Yunhe Cao 《Applied biochemistry and biotechnology》2010,160(5):1362-1370
The 1014 nucleotides long gene-encoding β-mannanase from Bacillus subtilis strain MA139 was cloned using PCR. To obtain high expression levels in Pichia pastoris, the β-mannanase gene was optimized according to the codon usage bias of P. pastoris and fused downstream of GAP promoter. The reconstituted plasmid pGAP-mann was transformed into P. pastoris X-33 strain to constitutively express β-mannanase. When cultured at 28 °C for 3 days protein yields up to 2.7 mg/mL was obtained
with the enzyme activity of up to 230 U/mL. In comparison, wild-type gene product yielded 1.9 mg/mL and 170 U/mL, respectively
indicating that the protein yield and enzyme activity were significantly improved by codon modification. After purification,
the enzyme properties were characterized. The optimal activity was at pH 6.0 and 50 °C. In the pH range of 3.0 to 9.0, β-mannanase
showed above 60% of its peak activity. Among the numerous ions tested copper significantly inhibited the enzyme activity.
These results suggested that codon-optimized β-mannanase expressed in P. pastoris could potentially be used as an additive in the feed for monogastric animals. 相似文献
6.
Bohumil Proksa Richard Hercek Tibor Liptaj Nada Prónayová 《Monatshefte für Chemie / Chemical Monthly》2009,140(5):485-487
Abstract A new compound was isolated from the reaction mixture after O-demethylation of 6-O-acetyl-10α-acetoxycodeine with boron tribromide. The structure of this compound, 10α-hydroxy-β-isomorphine, was elucidated by spectral data, and its spatial arrangement was deduced from an NOE experiment. Capillary zone
electrophoresis was used for separation of morphine and its 10-hydroxy analogues.
Graphical abstract
相似文献
7.
The crystalline modifications and of polypropylene (PP) were studied by using polarized light microscopy (PLM), wide-angle X-ray diffraction (WAXD), and differential scanning calorimetry (DSC). Typically crystals surrounded by spherulites were observed at low temperature. With increasing temperature the crystals melted and a new crystal appeared. More interestingly, the melting temperature of the new crystal was about 5 ° higher than that of spherulites originally present in the sample formed isothermally. It was assumed that this new crystal was the recrystalline crystal. This assumption was supported by the DSC results. Furthermore, the crystallization kinetics of the PP used was studied on the basis of the traditional Avrami analysis. As a result, the Avrami exponents of crystallization temperature from 120 to 130 °C ranged between 4.21 and 3.60, indicating that the crystallization mechanism of PP order melt was spherulitic growth and random nucleation. 相似文献
8.
O. A. Luk’yanov G. A. Smirnov P. B. Gordeev 《Russian Journal of Organic Chemistry》2007,43(8):1228-1231
A preparation method was developed for previously unknown tetrazole derivatives containing in the 1, 2, and/or 5 positions of the tetrazole ring N-methyldiazene-N-oxide-N′-oxymethyl groups. 相似文献
9.
Ai-Qun Lin Lin Du Yu-Chun Fang Fa-Zuo Wang Tian-Jiao Zhu Qian-Qun Gu Wei-Ming Zhu 《Chemistry of Natural Compounds》2009,45(5):677-680
A new natural product, iso-α-cyclopiazonic acid (1), together with its isomer α-cyclopiazonic acid (2); three mycotoxins: aflatoxin B1 (AFB1) (3), aflatoxin Q1 (AFQ1) (4), and O-methylsterigmatocystin (OMST) (5); two diketopiperazine alkaloids: ditryptophenaline (6) and 3-[(1H-indol-3-yl)methyl]-6-benzylpiperazine-2,5-dione (7), were isolated from the marine-derived fungus Aspergillus flavus. Their structures were determined by analysis of spectroscopic data. The cytotoxicities of compounds 1 and 2 were studied using HL-60, MOLT-4, A-549, and BEL-7402 cell lines. 相似文献
10.
Li S Zuo Z Niu D Singh S Permaul K Prior BA Shi G Wang Z 《Applied biochemistry and biotechnology》2011,164(5):581-592
A putative α-amylase gene, designated as RoAmy, was cloned from Rhizopus oryzae. The deduced amino acid sequence showed the highest (42.8%) similarity to the α-amylase from Trichoderma viride. The RoAmy gene was successfully expressed in Pichia pastoris GS115 under the induction of methanol. The molecular weight of the purified RoAmy determined by sodium dodecyl sulfate polyacrylamide
gel electrophoresis was approximately 48 kDa. The optimal pH and temperature were 4–6 and 60 °C, respectively. The enzyme
was stable at pH ranges of 4.5–6.5 and temperatures below 50 °C. Purified RoAmy had a K
m and V
max of 0.27 mg/ml and 0.068 mg/min, respectively, with a specific activity of 1,123 U/mg on soluble starch. Amylase activity
was strongly inhibited by 5 mM Cu2+ and 5 mM Fe2+, whereas 5 mM Ca2+ showed no significant effect. The RoAmy hydrolytic activity was the highest on wheat starch but showed only 55% activity
on amylopectin relative to soluble corn starch, while the pullulanase activity was negligible. The main end products of the
polysaccharides tested were glucose and maltose. Maltose reached a concentration of 74% (w/w) with potato starch as the substrate. The enzyme had an extremely high affinity (K
m = 0.22 mM) to maltotriose. A high ratio of glucose/maltose of 1:4 was obtained when maltotriose was used at an initial concentration
of 40 mM. 相似文献
11.
D. N. Olennikov A. V. Stolbikova A. V. Rokhin V. B. Khobrakova L. M. Tankhaeva 《Chemistry of Natural Compounds》2011,47(1):1-6
Water-soluble polysaccharides from Sophora flavescens (Fabaceae) roots were studied. The dominant polymer S
f
P-1-1/2 of molecular weight 85 kDa was isolated using ion-exchange and gel chromatography. The structure of the isolated
compound was α-(1→4)-glucan partially substituted at the C-6 position by single glucopyranose units. A pharmacological study showed that
S
f
P-1-1/2 exhibited under azathioprine suppression pronounced immunostimulating activity. 相似文献
12.
A. A. Shamitov I. K. Garkushin A. V. Kolyado E. P. Petrov 《Russian Journal of Physical Chemistry A, Focus on Chemistry》2018,92(2):300-303
The n-decane–n-hexadecane–cyclododecane, n-decane–cyclododecane, and n-hexadecane–cyclododecane systems are studied by means of low-temperature differential thermal analysis using a differential scanning heat flow calorimeter. It is noted that all studied systems belong to the eutectic type. It is concluded that in the n-decane–n-hexadecane–cyclododecane system, the eutectic composition contains 85.0 wt % n-С10Н22, 4.0 wt % n-С16Н34, and 11.0 wt % С12Н24. It has a melting point of ?35.0°C. 相似文献
13.
S. N. Gridchin 《Russian Journal of General Chemistry》2016,86(5):1069-1072
Stability constants and heat effects of the formation reactions of magnesium and calcium trimethylenediaminetetraacetates at 298.15 K and ionic strength of 0.1, 0.5, and 1.0 (mol/L KNO3) have been determined by means of potentiometry and calorimetry. Standard thermodynamic parameters (log K0, ΔrG0, ΔrH0, and ΔrS0) of the studied equilibriums have been determined. 相似文献
14.
The Diels–Alder reactions of three β-chloro-α,β-unsaturated carbonyl compounds 1–3 with different dienes were carried out to afford highly functionalized cyclohexenes 4–9, bearing quaternary centers, in good yields. These cycloadducts (CAs) undergo dehydrochlorination with subsequent aromatization in the presence of 1,8-diazabicyclo[5.4.0]undec-7-ene DBU to produce new substituted benzenes 11–14. Compound 10 is the product of lactonization and removal of an HCl molecule from compound 7. All products were characterized by NMR, IR, elementary analysis and some of them by MS. Structure assignments of isomers were carried out on the basis of NMR chemical shifts and coupling constants using 1D, 2D and heteronOe NMR techniques. 相似文献
15.
M. I. Kusaikin A. M. Zakharenko S. P. Ermakova M. V. Veselova E. V. Grigoruk S. A. Fedoreev T. N. Zvyagintseva 《Chemistry of Natural Compounds》2011,47(2):197-200
Maakia amurensis (strain A-18) cell culture synthesizes a significant quantity of isoflavonoids, a large part of which consists of isoflavone
glucosides and malonylglucosides. β−D-Hydrolase enzyme complexes from the marine mollusk Littorina sitkana and the marine mycelial fungus P. canescens were used to obtain isoflavones from their conjugated forms. The specificity of β−D-glucanases from L. sitkana for various glycosides was studied. The deglycosylation efficiency depended on the aglycon structure. The deglycosylated
fraction of isoflavonoids obtained from M. amurensis cell culture exhibited antitumor activity. 相似文献
16.
17.
β-Methoxycarbonyl-γ-butyrolactones bearing a γ-aromatic substituent were prepared via copper-catalyzed reductive aldol addition/lactonization domino reactions of ketones with α,β-unsaturated dicarboxylate esters and a silane under ambient temperature. The reaction has advantage of using readily available reagents, mild conditions and high efficiency. 相似文献
18.
Flávio José L. dos Santos Antônio Flávio de C. Alcântara Dalton L. Ferreira-Alves Dorila Piló-Veloso 《Structural chemistry》2008,19(4):625-631
This work describes the synthesis of new derivatives of 6α,7β-dihydroxyvouacapan-17β-oic acid (1) employing the Swern method for the oxidation of C-6 and C-7 of methyl 6α,7β-di-hydroxyvouacapan-17β-oate (2) and the formation of methyl 6,7-dioxovouacapan-17β-oate (3). NMR structural studies associated with theoretical calculations of reaction intermediates and products are also reported.
The mixture of methyl 7β-hydroxy-6-oxovouacapan-17β-oate (4; 21%) and methyl 6α-hydroxy-7-oxovouacapan-17β-oate (5; 79%) was the product from the first step of the oxidation of 2. The lower energy of 5, calculated by HF/6-31G* and DFT/BLYP/6-31G* methods, reinforces the thermodynamic control proposed for the reaction. After
further Swern oxidation of the mixture of 4 and 5, the isomeric form methyl 6-hydroxy-7-oxovouacap-5-en-17β-oate (6) was obtained. Theoretical calculations indicate a lower energy for the mono-enol 6 than the 1,2-diketo 3 and the other mono-enol methyl 7-hydroxy-6-oxovouacap-7-en-17β-oate (7). 相似文献
19.
Aruna P. Maharolkar A. G. Murugkar P. W. Khirade S. C. Mehrotra 《Russian Journal of Physical Chemistry A, Focus on Chemistry》2017,91(9):1710-1716
The refraction, dielectric, viscosity, density, data of the binary mixtures of N,N-dimethylacetamide (DMA) with n-butanol at 308.15 and 313.15 K. The measured parameters used to obtain derived properties like Bruggeman factor, molar refraction and excess static dielectric constant, excess inverse relaxation time, excess molar volume and excess viscosity, excess molar refraction. The variation in magnitude with composition and temperature of these quantities has been used to discuss the type, strength and nature of binary interactions. Results confirm that there are strong hydrogen-bond interactions between unlike molecules of DMA+ n-butanol mixtures and that 1: 1 complexes are formed and strength of intermolecular interaction increases with temperature. 相似文献
20.
Yasunori Matsui Minoru Shigemori Toshiyuki Endo Takuya Ogaki Eisuke Ohta Kazuhiko Mizuno Hiroyoshi Naito Hiroshi Ikeda 《Research on Chemical Intermediates》2018,44(8):4765-4774
The semiconductor properties of the earliest known stable radical, α,γ-bisdiphenylene-β-phenylallyl radical (Koelsch radical, 1?) were assessed using spectroscopic and electrical techniques. This radical undergoes reversible redox processes, and it has low redox potentials. In addition, 1? possesses long wavelength absorption bands, owing to the existence of a singly-occupied molecular orbital whose energy level lies between those of the HOMO and LUMO. A spin-coated thin-film of 1? displays photocurrent and an electron mobility of 6.3 × 10?7 cm2 V?1 s?1 on a trially-fabricated organic field effect transistor. 相似文献