Purification and characterization of recombinant murine endostatin in E. coli

Endostatin, a carboxyl-terminal fragment of collagen XVIII is known as an anti-angiogenic agent, that specifically inhibits the proliferation of endothelial cell and the growth of several primary tumor. We report here the purification and characterization of the recombinant murine endostatin (rmEndostatin) which was expressed in a prokaryotic expression system. This rmEndostatin has similar physiochemical properties of yeast-produced recombinant endostatin, and it also specifically inhibits the proliferation and migration of bovine capillary endothelial cells stimulated by basic fibroblast growth factor. The biological activity of rmEndostatin was also shown by its anti-angiogenic ability on the chorioallantoic membrane of chick embryo in vivo. In this article, we demonstrate the refolding and purification of rmEndostatin, expressed using E. coli system, to a biologically active and soluble form. In addition, these results confirm the activity of endostatin as a potent anti-angiogenic agent.     

Large-scale synthesis of TiO2 nanorods via nonhydrolytic sol-gel ester elimination reaction and their application to photocatalytic inactivation of E. coli

A simple method of synthesizing a large quantity of TiO(2) nanorods was developed. A nonhydrolytic sol-gel reaction between titanium(IV) isopropoxide and oleic acid at 270 degrees C generated 3.4 nm (diameter) x 38 nm (length) sized TiO(2) nanocrystals. The transmission electron microscopic image showed that the particles have a uniform diameter distribution. X-ray diffraction and selected-area electron diffraction patterns combined with high-resolution transmission electron microscopic image showed that the TiO(2) nanorods are highly crystalline anatase crystal structure grown along the [001] direction. The diameters of the TiO(2) nanorods were controlled by adding 1-hexadecylamine to the reaction mixture as a cosurfactant. TiO(2) nanorods with average sizes of 2.7 nm x 28 nm, 2.2 nm x 32 nm, and 2.0 nm x 39 nm were obtained using 1, 5, and 10 mmol of 1-hexadecylamine, respectively. The optical absorption spectrum of the TiO(2) nanorods exhibited that the band gap of the nanorods was 3.33 eV at room temperature, which is 130 meV larger than that of bulk anatase (3.2 eV), demonstrating the quantum confinement effect. Oleic acid coordinated on the nanorod surface was removed by the reduction of the carboxyl group of oleic acid, and the Brunauer-Emmett-Teller surface area of the resulting naked TiO(2) nanorods was 198 m(2)/g. The naked TiO(2) nanorods exhibited higher photocatalytic activity than the P-25 photocatalyst for the photocatalytic inactivation of E. coli.     

Asymmetric reduction of ketones with recombinant E. coli whole cells in neat substrates

The asymmetric reduction of ketones is performed by using lyophilized whole cells in neat substrates with defined water activity (a(w)). Ketones and alcohols prone to be unstable in aqueous media can now be converted via biocatalysis.     

Synthesis of deoxy derivatives of lactose and their hydrolysis by beta-galactosidase from E. coli.

Methyl 2-deoxy-alpha-lactoside, methyl 3-deoxy-beta-lactoside, 1,5-anhydro-4-O-beta-D-galactopyranosyl-D-glucitol and the 2-deoxy and 2,3-dideoxy derivatives of 1,5-anhydro-4-O-beta-D-galactopyranosyl-D-glucitol have been synthesized by deoxygenation of lactose derivatives at appropriate positions. Cyclohexyl beta-D-galactopyranoside has also been synthesized. All derivatives proved to be substrates for the enzyme beta-galactosidase from E. coli, but the rate of hydrolysis of the substrate analogues was strongly dependent on the nature of the aglycone.     

An efficient synthesis of chlorinated imidazoles through tert-butyldimethylsilyloxy derivatives

The protection of 2-substituted imidazole-5-methanol derivatives by tert-BDMS allowed the chlorination of the heterocycle in position 4 with good yield whereas direct chlorination on the imidazole alcohol was unsuccessful.     

Highly enantioselective and efficient synthesis of methyl (R)-o-chloromandelate with recombinant E. coli: toward practical and green access to clopidogrel

Methyl (R)-o-chloromandelate ((R)-), which is an intermediate for a platelet aggregation inhibitor named clopidogrel, was obtained in >99% ee by the asymmetric reduction of methyl o-chlorobenzoylformate (2) (up to 1.0 M) with recombinant E. coli overproducing a versatile carbonyl reductase.     

Asymmetric synthesis of fluorinated cyclic beta-amino acid derivatives through cross metathesis

The asymmetric synthesis of several fluorinated cis-2-aminocycloalkane carboxylic acids (cis-2-ACACs) with a cross metathesis (CM) reaction as the key step has been carried out, constituting the first time a metathesis protocol has been undertaken with fluorinated imidoyl chlorides. Subsequent chemoselective hydrogenation of the olefin moiety, Dieckmann condensation, and stereoselective reduction of the iminic double bond afforded the corresponding beta-amino esters with several ring sizes. The asymmetric version of the process was achieved by using (-)-8-phenylmenthol as a chiral auxiliary.     

Biocatalytic synthesis of gold nanoparticles with cofactor regeneration in recombinant Escherichia coli cells

Here we report the enzymatic synthesis of gold nanoparticles (Au NPs) by an engineered Escherichia coli harboring an NADH cofactor regeneration system coupled with glycerol dehydrogenase, which can be triggered by the addition of exogenous glycerol.     

An (E)-selective synthesis of trisubstituted (E)-alpha,beta-unsaturated acid derivatives

Potassium alkoxides of N-acyloxazolidin-2-one derived syn-aldolates undergo a novel tandem intramolecular cyclisation elimination reaction to afford trisubstituted (E)-alpha,beta-unsaturated amides in high d.e., which may be converted into their corresponding acids or oxazolines in good yield.     

Stereoselective synthesis of (E)-mannosylidene derivatives using the Wittig reaction

Stabilized ylides Bu(3)P=CH(EWG), where EWG is an ester or nitrile group, react with 2,3,4,6-tetra-O-benzylmannono-1,5-lactone giving high yields of mannosylidene derivatives; in contrast to the glucose and galactose analogues, the (E)-mannosylidenes are predominant (E:Z > 9:1), thus minimizing dipole-dipole repulsions in the Wittig reactions. NMR indicates chair-like conformations for solutions of the (E)-mannopyranosylidenes, but not for those (Z)-isomers where data are available (EWG = CN or CO(2)Et). X-ray crystallography shows an approximately twist-boat conformation for the tetra-O-benzyl-protected (Z)-mannosylideneacetonitrile.     

Catalytic synthesis of oligoene and enyne derivatives through carbometalation of internal alkynes

A number of new synthetic methods for π‐conjugated oligoene and enyne compounds are described. Thus, diene and higher oligoene derivatives are selectively constructed by palladium‐catalyzed arylation reactions of internal alkynes in the presence of arylboronic acids or alkenes as terminators. In contrast, the synthesis of various enyne derivatives is achieved effectively by homo‐ or cross dimerization of alkynes under rhodium catalysis. © 2008 The Japan Chemical Journal Forum and Wiley Periodicals, Inc. Chem Rec 8: 326–336; 2008: Published online in Wiley InterScience ( www.interscience.wiley.com ) DOI 10.1002/tcr.20158     

A practical synthesis of trans-3-substituted proline derivatives through 1,4-addition

A practical four-step synthesis of 3-alkyl-, vinyl-, and aryl-substituted proline derivatives, which are important building blocks for conformationally restrained peptide analogs, was developed. The method relies on a Cu-catalyzed 1,4-addition of Grignard reagents to N-protected 2,3-dehydroproline esters, efficiently prepared in a new one-pot protocol. The 1,4-addition products are obtained with good trans-selectivity (dr 5:1 to 25:1). A nonracemic sample of N-Cbz-3-vinylproline (74% ee) was obtained using Evans oxazolidinone as a chiral auxiliary.     

Efficient enantioselective synthesis of 3-aminochroman derivatives through ruthenium-Synphos catalyzed asymmetric hydrogenation

A highly enantioselective asymmetric hydrogenation of various trisubstituted enamides derived from chroman-3-ones promoted by cationic Ru-Synphos catalysts is reported. This atom-economical and clean method provides an efficient route to optically active 3-aminochroman derivatives, which are important pharmacophores found in numerous drug candidates, in high chemical yields and enantiomeric excesses up to 96%.     

Large-scale synthesis of single-crystalline perovskite nanostructures

Single-crystalline perovskite nanostructures with reproducible shape have been prepared using a simple, readily scaleable solid-state reaction in the presence of NaCl and a nonionic surfactant. Pristine BaTiO3 nanowires have diameters ranging from 50 to 80 nm with an aspect ratio larger than 25. Single-crystalline SrTiO3 nanocubes with a mean edge length of 80 nm have been produced using a similar procedure.     

An anti E. coli O157:H7 antibody-immobilized microcantilever for the detection of Escherichia coli (E. coli).

A silicon microcantilever sensor was developed for the detection of Escherichia coli O157:H7. The microcantilever was modified by anti-E. coli O157:H7 antibodies on the silicon surface of the cantilever. When the aquaria E. coli O157:H7 positive sample is injected into the fluid cell where the microcantilever is held, the microcantilever bends upon the recognition of the E. coli O157:H7 antigen by the antibodies on the surface of the microcantilever. A negative control sample that does not contain E. coli O157:H7 antigen did not cause any bending of the microcantilever. The detection limit of the sensor was 1 x 10(6) cfu/mL when the assay time was < 2 h.