ω-transaminase (ω-TA) is a natural biocatalyst that has good application potential in the synthesis of chiral amines. However, the poor stability and low activity of ω-TA in the process of catalyzing unnatural substrates greatly hampers its application. To overcome these shortcomings, the thermostability of (R)-ω-TA (AtTA) from Aspergillus terreus was engineered by combining molecular dynamics simulation assisted computer-aided design with random and combinatorial mutation. An optimal mutant AtTA-E104D/A246V/R266Q (M3) with synchronously enhanced thermostability and activity was obtained. Compared with the wild- type (WT) enzyme, the half-life t_1/2 (35 ℃) of M3 was prolonged by 4.8-time (from 17.8 min to 102.7 min), and the half deactivation temperature (T¹⁰₅₀) was increased from 38.1 ℃ to 40.3 ℃. The catalytic efficiencies toward pyruvate and 1-(R)-phenylethylamine of M3 were 1.59- and 1.56-fold that of WT. Molecular dynamics simulation and molecular docking showed that the reinforced stability of α-helix caused by the increase of hydrogen bond and hydrophobic interaction in molecules was the main reason for the improvement of enzyme thermostability. The enhanced hydrogen bond of substrate with surrounding amino acid residues and the enlarged substrate binding pocket contributed to the increased catalytic efficiency of M3. Substrate spectrum analysis revealed that the catalytic performance of M3 on 11 aromatic ketones were higher than that of WT, which further showed the application potential of M3 in the synthesis of chiral amines.
Transaminases/chemistry* ; Molecular Docking Simulation ; Amines/chemistry* ; Pyruvic Acid/metabolism* ; Enzyme Stability

Metastasis is one of the main reasons causing death in cancer patients. It was reported that chemotherapy might induce metastasis. In order to uncover the mechanism of chemotherapy-induced metastasis and find solutions to inhibit treatment-induced metastasis, the relationship between epithelial-mesenchymal transition (EMT) and doxorubicin (DOX) treatment was investigated and a redox-sensitive small interfering RNA (siRNA) delivery system was designed. DOX-related reactive oxygen species (ROS) were found to be responsible for the invasiveness of tumor cells in vitro, causing enhanced EMT and cytoskeleton reconstruction regulated by Ras-related C3 botulinum toxin substrate 1 (RAC1). In order to decrease RAC1, a redox-sensitive glycolipid drug delivery system (chitosan-ss-stearylamine conjugate (CSO-ss-SA)) was designed to carry siRNA, forming a gene delivery system (CSO-ss-SA/siRNA) downregulating RAC1. CSO-ss-SA/siRNA exhibited an enhanced redox sensitivity compared to nonresponsive complexes in 10 mmol/L glutathione (GSH) and showed a significant safety. CSO-ss-SA/siRNA could effectively transmit siRNA into tumor cells, reducing the expression of RAC1 protein by 38.2% and decreasing the number of tumor-induced invasion cells by 42.5%. When combined with DOX, CSO-ss-SA/siRNA remarkably inhibited the chemotherapy-induced EMT in vivo and enhanced therapeutic efficiency. The present study indicates that RAC1 protein is a key regulator of chemotherapy-induced EMT and CSO-ss-SA/siRNA silencing RAC1 could efficiently decrease the tumor metastasis risk after chemotherapy.
Amines/chemistry* ; Antineoplastic Agents/adverse effects* ; Breast Neoplasms/pathology* ; Chitosan/chemistry* ; Doxorubicin/adverse effects* ; Drug Delivery Systems ; Epithelial-Mesenchymal Transition/drug effects* ; Female ; Humans ; MCF-7 Cells ; Neoplasm Metastasis/prevention & control* ; Oxidation-Reduction ; RNA, Small Interfering/administration & dosage* ; Reactive Oxygen Species/metabolism* ; rac1 GTP-Binding Protein/physiology*

Tooth decay is prevalent, and secondary caries causes restoration failures, both of which are related to demineralization. There is an urgent need to develop new therapeutic materials with remineralization functions. This article represents the first review on the cutting edge research of poly(amido amine) (PAMAM) in combination with nanoparticles of amorphous calcium phosphate (NACP). PAMAM was excellent nucleation template, and could absorb calcium (Ca) and phosphate (P) ions via its functional groups to activate remineralization. NACP composite and adhesive showed acid-neutralization and Ca and P ion release capabilities. PAMAM+NACP together showed synergistic effects and produced triple benefits: excellent nucleation templates, superior acid-neutralization, and ions release. Therefore, the PAMAM+NACP strategy possessed much greater remineralization capacity than using PAMAM or NACP alone. PAMAM+NACP achieved dentin remineralization even in an acidic solution without any initial Ca and P ions. Besides, the long-term remineralization capability of PAMAM+NACP was established. After prolonged fluid challenge, the immersed PAMAM with the recharged NACP still induced effective dentin mineral regeneration. Furthermore, the hardness of pre-demineralized dentin was increased back to that of healthy dentin, indicating a complete remineralization. Therefore, the novel PAMAM+NACP approach is promising to provide long-term therapeutic effects including tooth remineralization, hardness increase, and caries-inhibition capabilities.
Amines ; pharmacology ; Calcium ; Calcium Phosphates ; chemistry ; pharmacology ; Dentin ; chemistry ; Humans ; Nanocomposites ; chemistry ; Nanoparticles ; Tooth Remineralization ; methods

Novel hydrogel composed of both chondroitin sulfate (CS) and gelatin was developed for better cellular interaction through two step double crosslinking of N-(3-diethylpropyl)-N-ethylcarbodiimide hydrochloride (EDC) chemistries and then click chemistry. EDC chemistry was proceeded during grafting of amino acid dihydrazide (ADH) to carboxylic groups in CS and gelatin network in separate reactions, thus obtaining CS–ADH and gelatin–ADH, respectively. CS–acrylate and gelatin–TCEP was obtained through a second EDC chemistry of the unreacted free amines of CS–ADH and gelatin–ADH with acrylic acid and tri(carboxyethyl)phosphine (TCEP), respectively. In situ CS–gelatin hydrogel was obtained via click chemistry by simple mixing of aqueous solutions of both CS–acrylate and gelatin–TCEP. ATR-FTIR spectroscopy showed formation of the new chemical bonds between CS and gelatin in CS–gelatin hydrogel network. SEM demonstrated microporous structure of the hydrogel. Within serial precursor concentrations of the CS–gelatin hydrogels studied, they showed trends of the reaction rates of gelation, where the higher concentration, the quicker the gelation occurred. In vitro studies, including assessment of cell viability (live and dead assay), cytotoxicity, biocompatibility via direct contacts of the hydrogels with cells, as well as measurement of inflammatory responses, showed their excellent biocompatibility. Eventually, the test results verified a promising potency for further application of CS–gelatin hydrogel in many biomedical fields, including drug delivery and tissue engineering by mimicking extracellular matrix components of tissues such as collagen and CS in cartilage.
Amines ; Cartilage ; Cell Survival ; Chemistry ; Chondroitin Sulfates ; Chondroitin ; Click Chemistry ; Collagen ; Extracellular Matrix ; Gelatin ; Hydrogel ; Hydrogels ; In Vitro Techniques ; Spectrum Analysis ; Tissue Engineering ; Transplants

OBJECTIVETo explore biomimetic mineralization of polyelectrolyte multilayer films (PEM) of gene-loaded lipopolysaccharide-amine nanopolymersomes/hyaluronic acid self assembled on titanium surface.

METHODSVia lay-by-layer self assembly technology, PEM were constructed on titanium or quartz surface using bone morphogenetic protein-2(BMP-2) plasmid-loaded lipopolysaccharide-amine nanopolymersomes(pLNP) as a polycation, and hyaluronic acid(HA) as a polyanion. The constructed PEM were defined as substrate-pLNP-(HA-pLNP)n, where a successive deposition of HA and pLNP on substrate surface was defined as one assembly cycle, and n was the cycle number. Biomimetic mineralization on surfaces of Ti-pLNP-(HA-pLNP)4(Group A, with outermost layer of pLNP), Ti-pLNP-(HA-pLNP)4.5(Group B, with outermost layer of HA), blank control(polished titanium, Ti) and alkaline-heat treated titanium(Ti-OH) were investigated. The biomimetic mineralization was analyzed by observing the topography under field-emisssion electron microscopy(FE-SEM), characterizing the surface chemical structure and components via X-ray diffractometer(XRD) and X-ray energy disperse spectroscopy(EDS).

RESULTSFor experiment groups, XRD analysis showed that the diffraction peak of hydroxyapatite appeared, and its intensity was higher than that for Ti group. FE-SEM images showed that its surface was homogeneously covered by discrete agglomerate of big particles. EDS spectra showed that the percentage of Ca and P were 77.24% and 64.23%, and these were much higher than those in Ti group.

CONCLUSIONSThe surface of Ti-pLNP-(HA-pLNP)n is favorable for in vitro biomimetic mineralization.

Amines ; chemistry ; Biomimetic Materials ; chemistry ; Bone Morphogenetic Protein 2 ; Durapatite ; chemistry ; Hyaluronic Acid ; chemistry ; Lipopolysaccharides ; Nanocomposites ; chemistry ; Plasmids ; Surface Properties ; Titanium ; chemistry

By structural modifications of our previous leads 1-3, 18 diarylamines were designed, synthesized and evaluated with a human tumor cell line panel, including A549, DU145, KB, and KB-vin cell lines, resulting in the discovery of new antitumor agents A6 and B2 with low micromolar G50 values ranging from 1.55-2.10 micromol x L(-1) for above cell lines, and A9 with GI50 values ranging from 1.55-2.10 micromol x L(-1) specially for DU145, KB, and KB-vin cells. Current structure-activity relationships are helpful for further lead optimization.
Amines ; chemical synthesis ; chemistry ; pharmacology ; Antineoplastic Agents ; chemical synthesis ; chemistry ; pharmacology ; Cell Line, Tumor ; Cell Proliferation ; drug effects ; Drug Design ; Drug Screening Assays, Antitumor ; Humans ; Molecular Structure ; Structure-Activity Relationship

Liver X receptor (LXR), a member of the superfamily of nuclear receptors, plays an important role in the activation of transcription factors involved in cholesterol metabolism, glucose homeostasis inflammation and lipogenesis. It is shown that LXR agnoists have the potentiality to be used as drugs for the prevention and treatment of atherosclerosis, which is its best investigated therapeutic indication. There are many compounds being studied in preclinical evaluation and biological assay. This paper will review briefly the LXR agonists in recent years.
ATP-Binding Cassette Transporters ; metabolism ; Amines ; chemical synthesis ; chemistry ; pharmacology ; Animals ; Atherosclerosis ; drug therapy ; metabolism ; Benzimidazoles ; chemical synthesis ; chemistry ; pharmacology ; Cholesterol ; analogs & derivatives ; pharmacology ; Glucose ; analogs & derivatives ; pharmacology ; Humans ; Lipid Metabolism ; Lipogenesis ; Liver X Receptors ; Orphan Nuclear Receptors ; agonists ; physiology ; Quinolines ; chemical synthesis ; chemistry ; pharmacology ; Sterol Regulatory Element Binding Protein 1 ; metabolism

The pharmaceutical properties, including the physical and chemical properties, and the bioavailability are greatly influenced by their polymorphism. In this paper the polymer heteronuclei were used to produce the gabapentin polymorphs that were characterized by X-ray powder diffraction, FT-IR and DSC. The results indicated that the polymer heteronuclei are an effective method to control and select the gabapentin polymorphism. One new polymorph of gabapentin was found besides all known gabapentin polymorphs.
Amines ; chemistry ; Anticonvulsants ; chemistry ; Calorimetry, Differential Scanning ; Crystallization ; Cyclohexanecarboxylic Acids ; chemistry ; Molecular Structure ; Polymers ; chemistry ; Spectroscopy, Fourier Transform Infrared ; X-Ray Diffraction ; gamma-Aminobutyric Acid ; chemistry

Polystyrene microspheres (PS) were successfully prepared by suspension polymerization processes. Chloroacetylated polystyrene has been prepared by Friedel-Crafts acetylation of PS with chloroacetyl chloride. In this report, carcinogenic compound (chloromethylether etc.) was avoided. The effects of solvent, catalyst, acylating agent and reaction time were studied. Novel adsorption resins were obtained by synthesis of chloroacetylated polystyrene with amine. The influences of solvent, amine reagent and reaction time on ion exchange capacity were investigated. Under the optimized reaction condition, the ion exchange capacity of the prepared resins was 4.1587 mmol/g. The maximum amount of adsorbed bilirubin was 30.85 mg/g, the adsorption percentage was 80%.
Acetates ; chemistry ; Adsorption ; Amines ; chemistry ; Bilirubin ; chemistry ; Humans ; Microspheres ; Polystyrenes ; chemical synthesis ; Porosity ; Resins, Synthetic ; chemical synthesis ; chemistry

The relationship of free amino groups on the surface and the characteristics of chitosan nanoparticles (CS-NPs) prepared by ionic gelation method was investigated. Free amino groups on the surface of CS-NPs were determined by colloidal titration, and the effects of the amount of free amino groups and its ionizable level on the particle size, zeta potential, appearance, drug entrapment efficiency and drug release profile in vitro of CS-NPs were investigated. The result showed that the surface free amino groups reduced, the average size, zeta potential, stability of nanoparticles, and the drug release rate and degree all decreased while the drug entrapment efficiency was not affected with the increase of tripolyphosphate (TPP) concentration. With the increase of pH, the free amino groups could be deprotonated and the ionizable level was stepped down, correspondingly the particle size and zeta potential of CS-NPs decreased. Additionally, the drug release rate and degree were elevated in acid medium while descended in neutral or base medium. The amount and ionizable level of free amino groups on the surface are affected by the gelation degree and pH, which further affected the volume phase transitions (swelling/shrinking processes) of CS-NPs. The properties of CS-NPs have correlation with the surface free amino groups.
Amines ; chemistry ; Chitosan ; chemistry ; Hydrogen-Ion Concentration ; Microscopy, Electron, Transmission ; Nanoparticles ; chemistry ; ultrastructure ; Particle Size ; Polyphosphates ; chemistry ; Surface Properties