Papers by Keyword: Peptide

Abstract: The study of the intermolecular interactions is important to explain the phenomenon occurred on the human body. One of the most important processes that can be studied is the interaction of the peptide with metal ions. In this study, a computational approach was harnessed to predict the interaction and the changes in peptide’s conformation between Cys-Ala peptide which is one of the important amino acids in e-cadherin with some of alkaline earth metal ions. Cys-Ala peptide (Ac-CA-NH₂) was used as a molecular model in this calculation. All the molecular structure involved in the interaction was optimized by density functional theory DFT/M06-2X, and basis set 6-31G** to obtain minimum energy, the interaction energies, and the changes in its conformation. The results showed that the interaction energy of Ac-CA-NH₂ with alkaline earth metal ions from top to bottom based on the Periodic table is getting higher in a row. The interaction energies of Ac-CA-NH₂ with Be²⁺, Mg²⁺ and Ca²⁺ ions are -2.393kcal, -17.489 kcal, and -25.938 kcal respectively. These energies were obtained from the interaction of the peptide with ions in a water solvent. The changes in the peptide's bond length and dihedral angle indicate a conformational change in the Cys-Ala peptide, but it still maintains the trans conformation in its peptide bonds. The results and evaluations of this study may be used for further research considerations and may be applied to enzymes or other peptides that have the Cys-Ala residue.

Abstract: Malaria caused by Plasmodium falciparum continues to be a major public health problem especially in tropical and sub-tropical regions of the world. Considering the growing resistance of parasites to anti-malarial drugs and of vector mosquitoes to insecticides, there is no doubt that the effective vaccine is the most awaiting tool to reduce the risk of malaria. Our synthetic studies have shown that a loop region (AD22 = ²⁵⁶ASEFYNSENKTYDLDFKTPNND²⁷⁷) of Plsmodium falciparum enolase has antigenic reactivity against patients’ sera and AD22 can produce inhibitory antibodies against in vitro parasite growth. In this paper, we will briefly present our ongoing research of malaria vaccine development and related model studies.

Abstract: Quantum dots (QDs) are powerful luminescent probes for detecting single-molecules and imaging live cells. Despite several reports on bioimaging and biosensing applications of QDs, controlled and targeted detection of biomolecules using quantum dots is an ongoing challenge. When a QD is conjugated with an ideal chromophore, which can be a fluorescent or a non-fluorescent dye molecule, QD luminescence can be quenched by Förster resonance energy transfer (FRET) to the quencher dye. However, the photoluminescence of QD can be recovered upon on-demand release of the quencher. Our study focuses on quenching of QD photoluminescence after conjugation with a non-fluorescent dye molecule, black hole quencher 1 (BHQ-1), intermediated with a molecular sensing target peptide GPLG↓VRGK. Based on steady-state and time-resolved photoluminescence measurements of QD and the QD-peptide-BHQ-1 sensor assemblies, we attribute the quenching of photoluminescence intensity and lifetime to FRET from the QD to BHQ-1molecules. Here the intermediate peptide GPLG↓VRGK can be cleaved by matrix metalloproteinase-2 (MMP-2), an enzyme that is upregulated in cancer cells extra cellular matrix (ECM), at its Gly and Val region shown by the down headed arrow. Here the QD-pep-BHQ-1 conjugate detected the MMP-2 presence at the extra cellular matrix of H1299 cancer cells. Further the QD-pep-BHQ-1 molecules were conjugated at the surface of a mesoporous silica nanoparticle (MSN) scaffold to localize maximum target peptide in a nanospace volume for the future αvβ3 integrin receptor targeted detection of MMP-2. The luminescence quenching of MSN-QD-pep-BHQ-1 conjugates were analyzed with time resolved photoluminescence measurement.

Abstract: A kind of peptide based Ni (II) complexes (general formula [ZN=C(An)-C(An)=NZ](NiBr₂)₂, Z=(4-NHR-3,5-C₆H₂(CH₃)₂)₂CH(4-C₆H₅), R=dipeptide, An=acenaphthenequinone) has been synthesized. Ethylene oligomerizations were carried out by using those complexes in combination with ethyl aluminium sesquichloride (EAS) and produced olefin . The effects of important parameters such as temperature and EAS concentration. on the catalytic activity and the distribution of resulting oligomer were investigated. under the conditions of employing toluene as solvent, a reaction temperature of 50°C and an ethylene pressure of 1.0 MPa..

Abstract: The major hurdles faced by therapeutic biomolecules to reach clinical use are non-specificity, unnecessary side effects, sensitivity to environmental factors and poor cellular uptake. Several nanoparticle systems have been developed to overcome these issues but there are still some bottlenecks such as nanoparticle toxicity, bioavailability and inability to track the biomolecules post-delivery. Here we report the use of multi-functional lanthanide-based fluorescent upconversion nanoparticles as a safe delivery vector for peptides as well as for fluorescent tracking of delivery or for in-vitro/in-vivo imaging. The UCNs are excited by a NIR light source and emit in the Visible region. Since NIR light is used for excitation, the nanoparticles could be used for deep tissue imaging. Highly monodisperse uniformly sized, sub-100 nm, biocompatible upconversion nanoparticles were synthesized with a mesoporous silica coating. Amanitin, a peptide toxin was used as a model peptide and was loaded onto the mesoporous silica coated UCNs. The peptide loaded UCNs were delivered to B16F0 melanoma cells and significant cell death was achieved within 24 hours. The unloaded UCNs however had negligible toxicity. The UCNs were also used for imaging the cells with very good signal-to-noise ratio and almost nil background autofluorescence. The fluorescence from the UCNs was non-blinking, highly stable and could be used for long-term tracking.

Abstract: Gold nanoflowers were simply produced in aqueous solution containing peptides (NH₂-Leu-Aib-Trp-Ome) and sodium dodecyl benzene sulfonate. HAuCl₄ was reduced by peptides. Scanning electron microscopy and transmission electron microscopy images show flower-like nanoparticles were about 50-100 nm. X-ray diffraction and electron diffraction patterns suggest face-centred cubic structures for these gold branched nanoparticles. There are three main stages in the growth of the gold nanoparticles: nanocrystal, aggregated nanoparticle, and flower-like nanostructure. The performance of the gold nanoflowers when used for surface enhanced Raman scattering was explored using crystal violet as the probe, which indicates that the these gold nanoflowers are promising for use as excellent surface enhanced Raman scattering substrates.

Abstract: There is a wide source of bioactive peptides and the preparation methods of it are various. It is a novel process that preparing bioactive peptides by genetic engineering. In this paper, the expression system of bioactive peptides is discussed and its research progress is introduced.

Abstract: The raspberry-like gold nanoparticles were synthesized with high yields following reduction with hydrochloroauric acid and peptide (Boc-Leu-Aib-Trp-OH) in methanol solution. Peptide acted as reducing agent. The prepared raspberry-like gold nanoparticles are effective application for surface-enhanced Raman scattering in ascorbic acid (Vc). Here, we also demonstrate the effective catalysts of raspberry-like gold nanoparticles for the activation and reduction of methylene blue in the presence of NaBH₄.

Abstract: Characteristics of solid state fermentation for soybean meals were studied in present paper. Effects of different factors on protease activity and peptides content during fermentation, using Bacillus Subtilis GA15 were explored. Optimal conditions of moisture content 50%, substrate height 2.5 cm at 36 °C for 72 h of incubation were obtained. Peptide content could be up to 14.37% in this condition. Moreover, the allergens in soybean meals were almost eliminated during fermentation according to SDS-PAGE profile.

Abstract: In this paper, graphene was used as the adsorbent for peptide enrichment, and followed by matrix-assisted laser desorption ionization-time of flight mass spectrometry (MALDI-TOF MS) analysis. To study the adsorptive property of graphene, peptide angiotensin II was chosen as the model target. The enrichment material was analyzed by MALDI-TOF MS directly without desorption step. As a result, graphene showed good adsorptive capacity for peptide. After enrichment, the peak intensity and the signal-to-noise ratio were obviously increased.