The demand for biomaterials with properties that provide sustained release of substances with pharmacological interest is constant. One candidate for applications in this area is the Natural Rubber Latex (NRL) extracted from the rubber tree Hevea brasiliensis. Recent studies indicate the NRL as a matrix for sustained release, showing promising results for biomedical applications such as: can stimulate natural angiogenesis and is capable of adhering cells on its surface, promoting the replacement and regeneration of tissue. So, the NRL is an excellent candidate to propitiate the sustained release of peptides of pharmacological interest such as oxytocin, a hormonal peptide which has the function to promote uterine muscle contractions and reduce bleeding during childbirth, and stimulate the release of breast milk. Results demonstrated that 90 μg mL?1 (45 %) of the incorporated peptide in Natural Rubber Latex Biomedical (NRLb) functionalized membranes was released at 10 h in phosphate-buffered saline (PBS) solution. Swelling kinetics assay showed that the NRLb membranes are able to absorb over a period of 16 h up to 1.08 grams of water per grams of membrane. Scanning electron microscopy showed that the peptide was adsorbed on the surface and within NRLb membrane. Fourier transform infrared and Derivative Thermogravimetric analysis indicated that oxytocin did not interacted chemically with the membrane. Furthermore, hemolysis of erythrocytes, quantified spectrophotometrically using materials (Oxytocin, NRLb, and NRLb + Oxytocin) showed no hemolytic effects up to 100 μg mL?1 (compounds and mixtures), indicating no detectable disturbance of the red blood cell membranes. Based on these results it was possible to conclude that the NRLb has shown effectiveness as a model in the release of peptides with pharmacological interest. 相似文献
Human gastrointestinal endogenous proteins (GEP) include the proteins mucins, serum albumin, digestive enzymes, and proteins from sloughed epithelial and microbial-cells. GEP play a vital role in the digestion of food, but are also simultaneously digested by proteases and peptidases of the gastrointestinal tract (GIT). Recent studies suggest that during gastrointestinal digestion, similar to dietary proteins, GEP may also give rise to bioactive peptides. In the present study, the protein sequences of 11 representative GEP were subjected to simulated in silico GIT (SIGIT) digestion. Following SIGIT digestion, 19 novel GEP-derived peptide sequences were selected using quantitative structure activity relationship rules for chemical synthesis. The peptides were then tested for their in vitro dipeptidyl peptidase IV (DPP-IV) and 2,2-diphenyl-1-picrylhydrazyl (DPPH) inhibition, and for their ferric reducing antioxidant power (FRAP). Two novel DPP-IV inhibitory peptides with the amino acid sequences RPCF (IC50 = 800.51 ± 49.00 µM) and MIM (IC50 = 1056.78 ± 61.11 µM), and five novel antioxidant peptides CCK, RPCF, CRPK, QQCP and DCR were identified. The results of this study indicate that GEP are a significant source of bioactive peptides with potential novel bioactive peptide fragments within their sequences. 相似文献
Chitobiase (CHB) is an important enzyme for the production of N-acetyl-d-glucosamine from the chitin biopolymer in the series of chitinolytic enzymes. Majority of over-expressed CHB (58 %) in E. coli expression system led to formation of inclusion bodies. The production and soluble yield of active CHB was enhanced by co-expression with GroEL/ES chaperonin, optimizing culture conditions and solubilization followed by refolding of remaining inactive chitobiase present in the form of inclusion bodies. The growth of recombinant E. coli produced 42 % CHB in soluble form and the rest (~58 %) as inclusion bodies. The percentage of active CHB was enhanced to 71 % by co-expression with GroEL/ES chaperonin system and optimizing culture conditions (37 °C, 200 rpm, IPTG—0.5 mM, l-arabinose—13.2 mM). Of the remaining inactive CHB present in inclusion bodies, 37 % could be recovered in active form using pulsatile dilution method involving denaturants (2 M urea, pH 12.5) and protein refolding studies (1.0 M l-arginine, 5 % glycerol). Using combinatorial approach, 80 % of the total CHB expressed, could be recovered from cells grown in one litre of LB medium is a step forward in replacing hazardous chemical technology by biotechnological process for the production of NAG from chitinous waste. 相似文献
Alzheimer’s disease is associated with the fibril formation of β-amyloid peptide in extracellular plaque. β-Casein is a milk protein that has shown a remarkable ability to stabilize proteins by inhibiting their protein aggregation and precipitation. The aim of this study was to test in vitro the ability of β-casein to bind the Aβ1–40, change the structure and inhibit the formation of amyloid fibrils in Aβ1–40. Results from the ThT binding assay indicated that incubation of Aβ1–40 with β-casein retarded amyloid fibril formation of Aβ1–40 in a concentration dependent manner such that at a ratio of 1:1 (w:w) led to a significant reduction in the amount of fluorescent intensity. The results from transmission electron microscopy (TEM) also showed that β-casein significantly reduced the number and size of the Aβ1–40 fibrils, suggesting that the chaperone bound to the Aβ1–40 fibrils and/or interacted with the fibrils in some way. ANS results also showed that β-casein significantly decreased the exposed hydrophobic surface in Aβ1–40. Following an ANS binding assay, CD spectroscopy results also showed that incubation of Aβ1–40 resulted in a structural transition to a β-sheet. In the presence of β-casein, however, α-helical conformation was observed which indicated stabilization of the protein. These results reveal the highly efficacious chaperone action of β-casein against amyloid fibril formation of Aβ1–40. These results suggest that in vitro, β-casein binds to the Aβ1–40 fibrils, alters the Aβ1–40 structure and prevents amyloid fibril formation. This approach may result in the identification of a chaperone mechanism for the treatment of neurological diseases. 相似文献
Cytokines such as interleukin-6 (IL-6) and IL-17 which act as key regulators of the immune response have been identified to have a potential role in the bone remodeling mechanism. Receptor activator of NF-κB ligand (RANKL) has been shown to regulate osteoclast differentiation and function while the osteoprotegerin (OPG) blocks the binding of RANKL and inhibits the differentiation of osteoclasts, thus favoring osteogenesis. Alkaline phosphatase (ALP) on the other hand works as early mineralization indicator in bone regulation. The current study aims to determine the potential role of IL-6 and IL-17A in regulating the OPG/RANKL system of the murine osteoblast cell line (MC3T3-E1). Gene expression analysis showed significant up-regulation of OPG and ALP by all the treated groups (rIL-6, rIL-17A and rIL-6 + rIL-17A). In contrast, treatment of cells with rIL-6 and/or rIL-17A showed down-regulation of RANKL expression. Interestingly, the osteoblast cells treated with combinations of rIL-6 + rIL17A showed marked increased in OPG/RANKL ratio. Similar pattern of protein expression was observed in the osteoblasts treated with rIL-6 and/or rIL-17A as detected by western blotting and ELISA. These findings suggest a new mechanism of regulation by these cytokines on the expression of OPG and RANKL, which could promote osteogenesis and diminish osteoclastogenesis. 相似文献
The COMPASS II force field has been developed by extending the coverage of the COMPASS force field (J Phys Chem B 102(38):7338–7364, 1998) to polymer and drug-like molecules found in popular databases. Using a fragmentation method to systematically construct small molecules that exhibit key functional groups found in these databases, parameters applicable to database compounds were efficiently obtained. Based on the same parameterization paradigm as used in the development of the COMPASS force field, new parameters were derived by a combination of fits to quantum mechanical data for valence parameters and experimental liquid and crystal data for nonbond parameters. To preserve the quality of the original COMPASS parameters, a quality assurance suite was used and updated to ensure that additional atom-types and parameters do not interfere with the existing ones. Validation against molecular properties, liquid and crystal densities, and enthalpies, demonstrates that the quality of COMPASS is preserved and the same quality of prediction is achieved for the additional coverage. 相似文献
The ternary complexes ML???PyZX2???NH3 (ML?=?CuCl, CuCN, AgCN, and AuCN; Z?=?P, As, and Sb; X?=?H and F) have been investigated with quantum chemical calculations. The results showed that the existence of coordination interaction has a prominent enhancing effect on the strength of pnicogen bonding. Even in ML???PySbH2???NH3, ML???PyAsF2???NH3, and ML???PySbF2???NH3, the pnicogen bond varies from a purely closed-shell interaction to a partially covalent interaction. The coordination interaction results in the enlargement of the σ-hole on the pnicogen atom and thus the enhancement of pnicogen bonding. In addition, the contribution of orbital interaction is also important.
Recently an iterative method was proposed to enhance the accuracy and efficiency of ligand-protein binding affinity prediction through linear interaction energy (LIE) theory. For ligand binding to flexible Cytochrome P450s (CYPs), this method was shown to decrease the root-mean-square error and standard deviation of error prediction by combining interaction energies of simulations starting from different conformations. Thereby, different parts of protein-ligand conformational space are sampled in parallel simulations. The iterative LIE framework relies on the assumption that separate simulations explore different local parts of phase space, and do not show transitions to other parts of configurational space that are already covered in parallel simulations. In this work, a method is proposed to (automatically) detect such transitions during the simulations that are performed to construct LIE models and to predict binding affinities. Using noise-canceling techniques and splines to fit time series of the raw data for the interaction energies, transitions during simulation between different parts of phase space are identified. Boolean selection criteria are then applied to determine which parts of the interaction energy trajectories are to be used as input for the LIE calculations. Here we show that this filtering approach benefits the predictive quality of our previous CYP 2D6-aryloxypropanolamine LIE model. In addition, an analysis is performed of the gain in computational efficiency that can be obtained from monitoring simulations using the proposed filtering method and by prematurely terminating simulations accordingly. 相似文献