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Electrospray ionization mass spectrometry was used to measure the binding of copper and nickel ions to the newly synthesized model peptides H2N–AAAAHAAAAHAAAAHAAAA–COOH (P19–H5) and H2N–AAAHAAAHAAAHAAAAAAA–COOH (P19–H4). The affinity of... more
Electrospray ionization mass spectrometry was used to measure the binding of copper and nickel ions to the newly synthesized model peptides H2N–AAAAHAAAAHAAAAHAAAA–COOH (P19–H5) and H2N–AAAHAAAHAAAHAAAAAAA–COOH (P19–H4). The affinity of histidine-containing peptides toward heavy metal ions proved to be related to the position of each histidine residue in the peptide sequence. In contrast to P19–H5, P19–H4 peptide bound no nickel or copper ions in the gas phase, whereas its spectra showed an intense fragmentation. The role of spacing residues (Ala repeats) in selecting the various conformations was also investigated. Finally, the circular dichroism and Fourier transform infrared spectra indicated that these isomer peptides have quite different conformations. A close relationship between the conformation of alanine-based peptides and their affinity toward metal ions may result in different patterns of metal ion-peptide systems.
Research Interests: Chemistry, Analytical Chemistry, Mass Spectrometry, Medicine, Circular Dichroism, and 10 moreCopper, Nickel, Peptide, High Pressure Liquid Chromatography, Liquid Chromatography / Electrospray Ionization Mass Spectrometry, Fourier transform infrared spectroscopy, Protein Conformation, Protein Binding, Histidine, and Electrospray Ionization
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Halobacterium salinarum is an extremely halophilic marine Gram-negative obligate aerobic archaeon. Despite its name, this is not a bacterium, but rather a member of the domain Archaea, which lives in hypersaline lakes. Bacteriorhodopsin... more
Halobacterium salinarum is an extremely halophilic marine Gram-negative obligate aerobic archaeon. Despite its name, this is not a bacterium, but rather a member of the domain Archaea, which lives in hypersaline lakes. Bacteriorhodopsin (BRh) is the red retinal-containing protein found in the cell membranes of H. salinarum and is considered a light-activated proton pump that transports protons across the plasma membrane. Bacteriorhodopsin photointermediates have been defined in kinetic and spectroscopic terms as BR568, K590, L550, M412, N560, and O640. We have previously shown, using the Forster cycle for BRh that its acidity increases greatly on illumination. Therefore, protons released upon illumination of the L550 intermediate with 412 nm light may not play an essential role in ATP production. Instead, the light-induced excitation energy, which represents the energy difference between the L550 and M412 states, can be used to extract an ATP molecule attached to ATP synthase. Thus, we have shown that this amount of energy corresponds to a near-infrared vibration, which is sufficient for ATP production and provides the most feasible molecular mechanism for this phenomenon. Here, we provide new evidence that protons are released due to BRh excitation, unrelated to ATP synthesis, being only a secondary phenomenon. In addition, once released from H. salinarum cells, protons should return back into the cells via ATP-synthase molecules to produce ATP. This is not possible at pH > 7.0, such as pH 9.5. However, the stability of M intermediates and ATP formation appear to be increased at higher pH values. Indeed, a spectral shift of 138 nm may be associated with an energy amount of about 17 kcal mol-1, which is enough energy to release a mole of ATP from ATP-synthase. In general, light excitation of fluorescent molecules is a phenomenon that induces a strong increase in their acidity. Recent data suggest that the chemiosmotic hypothesis put forward by Peter Mitchell to explain ATP formation in living cells is not correct, at least in terms of explaining light-induced ATP production in H. salinarum cells.
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Research Interests: Chemistry and Germination
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Spectrophotometric methods for total protein analysis are generally simple, rapid and sensitive. Such sensitive protein assays may have applications in forensic science, in the detection of protein contaminants in drugs and in a number of... more
Spectrophotometric methods for total protein analysis are generally simple, rapid and sensitive. Such sensitive protein assays may have applications in forensic science, in the detection of protein contaminants in drugs and in a number of other applications of research interest. Biuret reaction with proteins and peptides is widely used in clinical and biological laboratories. In this work, instead of copper sulphate, sodium hydroxide and Seignette salt, we used insoluble copper phosphate, potassium or sodium hydroxide and ethyl alcohol for the preparation of the biuret reagent. Absorbance of the biuret complex was recorded both at 219-230 nm (after dilution) and around 550 nm against a reagent blank. Amino acid interference was investigated around 550 nm at the same concentration as proteins. The sensitivity of the method at 226 nm was greater than those of other spectrophotometric assays (old biuret method, Lowry, and BCA) with a LOD of about 0.5 �g mL?1 BSA. The new variants of th...
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Peptides and their related compounds can self-assemble into diverse nanostructures of different shapes and sizes in response to various stimuli such as pH, temperature or ionic strength. Here we report the synthesis and characterization... more
Peptides and their related compounds can self-assemble into diverse nanostructures of different shapes and sizes in response to various stimuli such as pH, temperature or ionic strength. Here we report the synthesis and characterization of a lysozyme derived pentapeptide and its ability to build well-defined fibrillar structures. Lysozyme FESNF peptide fragment was synthesized by solid phase peptide synthesis using the Fmoc/t-Bu strategy, purified by analytical high-performance liquid chromatography (HPLC) and its molecular weight was confirmed by matrix-assisted laser desorption/ionization mass spectrometry (MALDI–MS). Spectroscopic features of this pentapeptide were investigated by UV-visible spectroscopy and fluorimetry showing the pattern of marginal phenylalanine residues within the peptide sequence. Self-assembling properties were determined using atomic force microscopy (AFM), aggregation index and thioflavin T assay (ThT). FESNF generating fibrillar structures observed by AF...
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Our work discusses the investigation of 75 peptide-based drugs with the potential ability to break the β-sheet structures of amyloid-beta peptides from senile plaques. Hence, this study offers a unique insight into the design of... more
Our work discusses the investigation of 75 peptide-based drugs with the potential ability to break the β-sheet structures of amyloid-beta peptides from senile plaques. Hence, this study offers a unique insight into the design of neuropeptide-based drugs with β-sheet breaker potential in the amyloid-beta cascade for Alzheimer’s disease (AD). We started with five peptides (15QKLVFF20, 16KLVFF20, 17LVFF20, 16KLVF19 and 15QKLV18), to which 14 different organic acids were attached at the N-terminal. It was necessary to evaluate the physiochemical features of these sequences due to the biological correlation with our proposal. Hence, the preliminary analysis of different pharmacological features provided the necessary data to select the peptides with the best biocompatibility for administration purposes. Our approaches demonstrated that the peptides 17LVFF20, NA-17LVFF20, 16KLVF19 and NA-16KLVF19 (NA-nicotinic acid) have the ability to interfere with fibril formation and hence improve the...
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In order to emphasize modifications on living organisms resulted from interaction with heavy metals, we applied a simple, sensitive, quick, inexpensive and reproducible method. It evaluates modifications through determining released amino... more
In order to emphasize modifications on living organisms resulted from interaction with heavy metals, we applied a simple, sensitive, quick, inexpensive and reproducible method. It evaluates modifications through determining released amino acids. This method comprises three stages: treating plants with the investigated heavy metals, extracting resulted amino acids and dosing them with a ninhydrin reagent. The colored solution resulted from ninhydrin dosing is spectrophotometrically measured at 516 nm. The Lambert-Beer law is valid within the concentration field of 0-20 μg mL–1. .
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Carbon monoxide (CO) and hydrogen cyanide (HCN) are two common toxic products of combustion. HCN concentrations of fire victims are not routinely determined in most legal medicine services in Romania. We present the case of a room fire... more
Carbon monoxide (CO) and hydrogen cyanide (HCN) are two common toxic products of combustion. HCN concentrations of fire victims are not routinely determined in most legal medicine services in Romania. We present the case of a room fire victim in which we evaluated the concentrations of HCN and carboxyhemoglobin (COHb), their contribution to the mechanism of death, and the possibility that HCN concentration can be interpreted as vital sign. COHb was determined by spectrophotometry. HCN was spectrophotometrically determined with ninhydrin in postmortem blood samples after its removal with 20% phosphoric acid and uptake into a solution of potassium carbonate. The presence of ethyl alcohol was determined by gas chromatography. The COHb concentration was 6.15%, while the blood HCN concentration was 1.043 µg × mL−1 and the total HCN was 1.904 µg × ml−1. A blood alcohol content of 4.36 g‰ and a urine alcohol content of 5.88 g‰ were also found. Although the fire produced a considerable amou...
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The content of vitamin C, carotenes, polyphenols, total carbohydrates and total soluble proteins was determined, alongside with the activity of the oxidative stress enzymes (superoxide-dismutase, catalase, peroxidase,... more
The content of vitamin C, carotenes, polyphenols, total carbohydrates and total soluble proteins was determined, alongside with the activity of the oxidative stress enzymes (superoxide-dismutase, catalase, peroxidase, isocitrat-dehydrogenase, ketoglutarat-dehydrogenase, succinat-dehydrogenase and malat-dehydrogenase) in Rosa canina L. samples collected from the heavy metals and arsenic polluted area around of Tarni�a closed mine, as well as from Sucevita area (as unpolluted site). The results showed an increase in the rose hip richness of nutrients and biological-active compounds, as well as the antioxidant activity of the samples from Tarnita area.We have explained our results taking into consideration the response of rosa plants to the oxidative stress produced by the accumulation of reactive oxygen species generated byexposure to pollutant factors from the contaminated area.
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This paper presents the results from a study on the current state of tailing dump, surrounding soil and water in the region of Tarniţa-Suceava, Romania. A number of chemical analyses and germination tests were applied in an attempt to... more
This paper presents the results from a study on the current state of tailing dump, surrounding soil and water in the region of Tarniţa-Suceava, Romania. A number of chemical analyses and germination tests were applied in an attempt to estimate the ability of soil to maintain the plants growing, the bioavailability, and heavy metals uptake. Total heavy metals, exchangeable metals, acidity, and carbon and nitrogen content were determined. A modified sequential extraction method was used to determine geochemical phase distribution of heavy metals. The most abundant heavy metals in the studied samples were Cu, Zn, and Pb. Elevated concentrations of As were also found. The results from sequential extraction revealed that up to 51% of copper was retained by amorphous and crystalline iron oxides in soil. Higher content of lead was noticed in amorphous iron oxide fraction. The heavy metal concentration in river water during dry season varied from 0.13 mg/L (Fe) to 4.2 mg/L (Zn) and was below the maximum contamination level for drinking water. The soil toxicity and heavy metal bioavailability of tailing dump material and surrounding soils were studied by germination tests. The germinated plantlets on the studied soils were found to accumulate elevated concentrations of heavy metals thus indicating the bioavailability of soil contaminants. Soil decontamination by distilled water or magnesium nitrate solution was found to be efficient enough to improve the capability of the studied soils to support the germination process.
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In the present paper, the interaction between copper ions and proteins is presented, in order to elaborate a simple and rapid spectrophotometric assay of casein in milk. Under alkaline conditions, copper ions form the biuret complex with... more
In the present paper, the interaction between copper ions and proteins is presented, in order to elaborate a simple and rapid spectrophotometric assay of casein in milk. Under alkaline conditions, copper ions form the biuret complex with the proteins, which can be used in protein determination. Although very specific, the biuret method is less sensitive. Using insoluble copper phosphate, casein is able to extract copper ions, with which it forms the biuret complex, while either the complex or copper ions could be determined in the ultraviolet range. Indeed, an increased absorbance of biuret complex at 215 nm was found. Nevertheless, copper ions can be determined in UV as well, their concentration being proportional to that of casein. When used tetraglycine instead casein, mass spectrometric measurements at pH higher than 11 revealed the formation of complexes with many copper ions bound to each peptide bond-containing molecule. Nevertheless, on diluting the biuret solution the compl...
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Bioinspired peptides are attractive biomolecules which can improve our understanding of self-assembly processes for rational design of new peptide-based materials. Herein, a new amidated peptide FRSAPFIE (FRS), based on a sequence present... more
Bioinspired peptides are attractive biomolecules which can improve our understanding of self-assembly processes for rational design of new peptide-based materials. Herein, a new amidated peptide FRSAPFIE (FRS), based on a sequence present in human collagen, was synthesized, characterized by mass spectrometry and subjected to self-assembling investigations. The optimal conditions for self-assembly were disclosed by dynamic light scattering at 32 °C and a peptide concentration of 0.51 %. In addition, AFM studies revealed ellipsoidal FRS shapes with an area between 0.8 and 3.1 μm2 . The ability of self-assembly was also proved using FAD dye as extrinsic fluorescence reporter. According to the theoretical analysis, the FRS peptide tends to form a bundle-type association, with a type of fibrillary tangles particle. Altogether, our findings address new challenges regarding the FRS peptide which can be used in further self-assembly studies to design biocompatible drug-delivery platforms.
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OLGA PINTILIE1, MARIUS ZAHARIA2*, ADELINA COSMA2, MANUELA MURARIU3, ROBERT GRADINARU2, GHEORGHE G. BALAN4, GABI DROCHIOIU2, ION SANDU1,5* 1 Al. I. Cuza University of Iasi, Department of Geography and Geology, 11 Carol I Blvd., 700506,... more
OLGA PINTILIE1, MARIUS ZAHARIA2*, ADELINA COSMA2, MANUELA MURARIU3, ROBERT GRADINARU2, GHEORGHE G. BALAN4, GABI DROCHIOIU2, ION SANDU1,5* 1 Al. I. Cuza University of Iasi, Department of Geography and Geology, 11 Carol I Blvd., 700506, Iasi, Romania 2Al. I. Cuza University of Iasi, Department of Chemistry, 11 Carol I Blvd., 700506, Iasi, Romania, 3Petru Poni Institute of Macromolecular Chemistry, 41A Gr. Ghica Voda Alley, 700487, Iasi, Romania 4 Grigore T. Popa University of Medicine and Pharmacy, Faculty of Dental Medicine, 16 Universitatii Str., 700115, Iasi, Romania 5ARHEOINVEST Interdisciplinary Platform, Laboratory of Scientific Investigation and Conservation of Cultural Heritage, Al. I. Cuza University of Iasi, 22 Carol I, 700506, Iasi, Romania
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Heavy metal pollution of ecosystems is of great concern, due to the persistence of metals in ecosystem. In this regard, the mountainous pastures of Romanian Carpathians, especially those in the areas of abandoned mines, need particular... more
Heavy metal pollution of ecosystems is of great concern, due to the persistence of metals in ecosystem. In this regard, the mountainous pastures of Romanian Carpathians, especially those in the areas of abandoned mines, need particular attention. The aim of this work was to assess the effect of heavy metals and metalloids exposure on cuticular wax composition of tall fescue leaves (Festuca arundinacea). Therefore, we have particularly investigated the variations of long chain hydrocarbon fractions, which are acknowledged to act as a protection for plants especially in toxic environments. The exposure experiments were conducted in triplicates for arsenic and the following metal ions: Ba2+, Cu2+, Fe2+ and Pb2+. The 0.5 mM aqueous solutions of their corresponding salts were used as treatment solutions. Triplicate experiments were also performed for control samples using distilled water as exposure media. The plantlets were kept for growing in controlled environment for 15 days followed...
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Studies to test the noxious effect of mercury ions on wheat germination and seedling growth showed that germination rate, shoot length, and fresh weights varied as a function of their concentration in the treatment solutions. At the same... more
Studies to test the noxious effect of mercury ions on wheat germination and seedling growth showed that germination rate, shoot length, and fresh weights varied as a function of their concentration in the treatment solutions. At the same concentration, the radioactive mercury proved to be more harmful to the living seeds and seedlings. The detoxification action of glutathione for both radioactive and non-radioactive mercury was also followed. After a seven-day period of germination in the presence of the investigated compounds, the wheat plantlets were cut from the seeds, and their height, weight, and residual radioactivity were measured. The shoot length decreased from 8.1 (blank) to 4.6 cm (non-radioactive mercury) or even to 2.5 cm ((203)Hg), while glutathione had both an anti-toxic and an anti-radiotoxic effect (6.4 and 6.0 cm, respectively). The root weight of the lot decreased from 1.7 to 0.7 g and 0.4 g, respectively, while glutathione showed a healing action (1.5 and 1.7 g). The radioactive ions accumulated especially in roots (35.5 %), and less in shoots (11.2 %). Results were statistically validated.
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Electrospray ionization mass spectrometry was used to measure the binding of copper and nickel ions to the newly synthesized model peptides H2N–AAAAHAAAAHAAAAHAAAA–COOH (P19–H5) and H2N–AAAHAAAHAAAHAAAAAAA–COOH (P19–H4). The affinity of... more
Electrospray ionization mass spectrometry was used to measure the binding of copper and nickel ions to the newly synthesized model peptides H2N–AAAAHAAAAHAAAAHAAAA–COOH (P19–H5) and H2N–AAAHAAAHAAAHAAAAAAA–COOH (P19–H4). The affinity of histidine-containing peptides toward heavy metal ions proved to be related to the position of each histidine residue in the peptide sequence. In contrast to P19–H5, P19–H4 peptide bound no nickel or copper ions in the gas phase, whereas its spectra showed an intense fragmentation. The role of spacing residues (Ala repeats) in selecting the various conformations was also investigated. Finally, the circular dichroism and Fourier transform infrared spectra indicated that these isomer peptides have quite different conformations. A close relationship between the conformation of alanine-based peptides and their affinity toward metal ions may result in different patterns of metal ion-peptide systems.
Research Interests: Chemistry, Analytical Chemistry, Mass Spectrometry, Medicine, Electrospray, and 10 moreCopper, Metal, Nickel, High Pressure Liquid Chromatography, Liquid Chromatography / Electrospray Ionization Mass Spectrometry, Fourier transform infrared spectroscopy, Protein Conformation, Protein Binding, Histidine, and Electrospray Ionization
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Research Interests: Engineering, Chemistry, Mass Spectrometry, Medicine, Biological Sciences, and 14 moreCircular Dichroism, Copper, Metal, Peptide, CHEMICAL SCIENCES, Protein Secondary Structure, Protein Secondary Structure Prediction, Protein Conformation, Amino Acid Sequence, Conformational Change, Biomacromolecules, Molecular Sequence Data, Sodium Dodecyl Sulfate, and Medical and Health Sciences
Research Interests: Chemistry, Mass Spectrometry, Biophysical Chemistry, Atomic Force Microscopy, Medicine, and 15 moreBiological Sciences, Circular Dichroism, Copper, Silver, Heavy Metal, Physical sciences, Nickel, Metals, CHEMICAL SCIENCES, Water Loss, Ion, Metal ion, Protein Binding, Binding Site, and Conformational Change
Neurodegenerative diseases, including Alzheimer disease, involve mechanisms such as protein aggregation, free radical generation and oxidative stress. Transition metals such as copper and iron were linked to neurodegenerative pathology.... more
Neurodegenerative diseases, including Alzheimer disease, involve mechanisms such as protein aggregation, free radical generation and oxidative stress. Transition metals such as copper and iron were linked to neurodegenerative pathology. Their pathogenic role consists in generating different reactive oxygen species and damaging tissues or cells through the Fenton reaction. Abnormal metabolism of copper and iron can lead to several chronic pathogenesis. NAP is a small active fragment of activity-dependent neuroprotective protein essential for brain formation. NAP peptide showed neuroprotective proprieties against toxicity induced by the �-amyloid peptide, N-methyl-D-aspartate, electrical blockade, the envelope protein of the AIDS virus, dopamine, H2O2, and nutrient starvation in cell culture. Therefore, we investigated here the interaction of Cu2+ and Fe3+ ions with the NAP neuroprotective peptide and its analogs. With MALDI-ToF mass spectrometry, the formation of reduced metal-peptid...
Heavy metals are destructive environmental stressors that greatly reduce plant growth and productivity. Here, the content of some heavy metals (Fe, Cu, Zn and Mn) and mineral nutrients (Ca, Mg and K) in silver fir (Abies alba Mill.) and... more
Heavy metals are destructive environmental stressors that greatly reduce plant growth and productivity. Here, the content of some heavy metals (Fe, Cu, Zn and Mn) and mineral nutrients (Ca, Mg and K) in silver fir (Abies alba Mill.) and European beech (Fagus sylvatica L.) wood from two sites in the Tarni�a mining area (North-Est Romania) was analyzed. The first site (no. 1) is located near a big tailings dump, whereas the other one (no. 2) is situated 6 km South, in a less polluted area. The purpose of this work was to evaluate the present-date levels of such elements in the investigated biological materials and to compare them. Measurements of heavy metal content in wood were performed with an AAS flame spectrometer, whereas an ICP-OES spectrometer was used for soil and tailings dump samples. The Mn content was higher in the site no. 1 located near the dump, for both species, but the difference was statistically significant only for the European beech trees. The Zn content of sampl...
Ninhydrin reagents are currently used for amino acid determination. However, ninhydrin reacts with amino groups of amino acids and other components of palmar sweat to develop Ruheman’s purple. Therefore, it was used on a large scale to... more
Ninhydrin reagents are currently used for amino acid determination. However, ninhydrin reacts with amino groups of amino acids and other components of palmar sweat to develop Ruheman’s purple. Therefore, it was used on a large scale to fingerprint development. Another recent application of ninhydrin is related to trace cyanide detection and determination. However, this simple compound may have multiple applications in peptide and protein research, in drug identification and detection or in heterocycle synthesis. Mainly, detection of finger marks with ninhydrin at a crime scene is of prime interest for forensic investigators. Herein, we review the most significant forensic applications of ninhydrin and its derivatives.
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The possibility of bioaccumulation of uranium species in beer yeast was investigated. The behaviour of the Saccharomyces cerevisiae-UO2 system was studied vs. contact time, pH and anion nature with no ionic competition. Analysis of the... more
The possibility of bioaccumulation of uranium species in beer yeast was investigated. The behaviour of the Saccharomyces cerevisiae-UO2 system was studied vs. contact time, pH and anion nature with no ionic competition. Analysis of the data revealed the following optimal working conditions: contact time = 1 h, pH = 6.5 and 10 −1 M UO2(CH3COO)2 solution as uranyl source; as a result, the maximum degree of bioaccumulation attends a value nearly 8.75 mmol UO2 2+ /g yeast. Both, a scanning electron microscope (SEM) and amino acid determinations lead to the conclusion that the uranyl nitrate solution may devastate the yeast cells provoking membrane damage and the release of the cell constituents (including the bioaccumulated uranium species). The results suggest the possible use of Saccharomyces cerevisiae as a biological decontaminant of uranium containing wastewaters.
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Pyridazine compounds have an intense biological activity, being used as anticancer, antituberculosis, antihypertensive, antifungal, or antimicrobial agents. Nevertheless, some of them might be noxious persistent compounds to the... more
Pyridazine compounds have an intense biological activity, being used as anticancer, antituberculosis, antihypertensive, antifungal, or antimicrobial agents. Nevertheless, some of them might be noxious persistent compounds to the environment. Therefore, several studies to test the biologic effect of some new pyridazine derivatives have been done using simple experiments of wheat germination. The germination percentage, shoot and root length, fresh weights, as well as free amino acid content varied as a function of concentration and structure of each investigated compound. Triplicate of 50seed samples of wheat were treated with 5∙10 -3 molar solutions of both pyridazinium bromides (2ac) and the corresponding cycloadducts (49) for 1 hour. After a 7day period of germination in the presence of the investigated compound, the wheat plantlets were cut from the seeds. The total height (H) of the lots and the weight (W) of the seedlings, as well as the free amino acids were measured. Amon...
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Le travail presente le dosage des cyanures dans l'eau d'analyse ou d'autres fluides comme le sang, le serum ou l'urine, par l'inhibition de l'activite catalytique de l'acide cyanhydrique resulte par... more
Le travail presente le dosage des cyanures dans l'eau d'analyse ou d'autres fluides comme le sang, le serum ou l'urine, par l'inhibition de l'activite catalytique de l'acide cyanhydrique resulte par l'action de l'acide sulfurique. L'acide cyanhydrique forme est capte dans une solution de KOH. Pour 1 mL de distille, qui contient 0-2 μg CN-, on ajoute 0,5 mL de l'eau oxygenee et une solution de catalase. La concentration de l'eau oxygenee restee non decomposee est determinee quantitativement par iodometrie. L'absorbance optique de la solution de couleur bleue est mesuree a 630 nm.
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Aggregation of amyloid-β peptides (Aβ) is a hallmark of Alzheimer’s disease (AD), which is affecting an increasing number of people. Hence, there is an urgent need to develop new pharmaceutical treatments which could be used to prevent... more
Aggregation of amyloid-β peptides (Aβ) is a hallmark of Alzheimer’s disease (AD), which is affecting an increasing number of people. Hence, there is an urgent need to develop new pharmaceutical treatments which could be used to prevent the AD symptomatology. Activity-dependent neuroprotective protein (ADNP) was found to be deficient in AD, whereas NAP, an 8-amino-acid peptide (1NAPVSIPQ8) derived from ADNP, was shown to enhance cognitive function. The higher tendency of zinc ion to induce Aβ aggregation and formation of amorphous aggregates is also well-known in the scientific literature. Although zinc binding to Aβ peptides was extensively investigated, there is a shortage of knowledge regarding the relationship between NAP peptide and zinc ions. Therefore, here, we investigated the binding of zinc ions to the native NAP peptide and its analog obtained by replacing the serine residue in the NAP sequence with tyrosine (1NAPVYIPQ8) at various molar ratios and pH values by mass spectr...
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NAP (NAPVSIPQ) is a small peptide derived from the activity-dependent neuroprotective protein (ADNP), which provides neuroprotection against amyloid-β peptide toxicity associated with Alzheimer disease. Several metal ions are able to... more
NAP (NAPVSIPQ) is a small peptide derived from the activity-dependent neuroprotective protein (ADNP), which provides neuroprotection against amyloid-β peptide toxicity associated with Alzheimer disease. Several metal ions are able to promote the formation of amyloid-β peptide oligomers and protofibrils in human brain tissue. Although the relationship between metal ions and amyloid-β peptide peptides is extensively investigated, that with the NAP peptide is less understood. Nevertheless, our previous research revealed unexpected iron binding to NAP peptide and its analogs. However, a link between aluminum ions, Alzheimer disease and amyloid-β peptide or NAP peptides still remains controversial. Therefore, we have investigated the possible binding of aluminum ions to NAP peptide and its four analogs. Indeed, MALDI-ToF mass spectrometry (MS), including MS/MS study, and Fourier transform infrared (FT-IR) spectroscopy revealed an unexpected pattern of aluminum ion binding to both NAP pep...
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Heavy metal ions and those of aluminum may interact with amyloid-β peptides (Αβ) associated with Alzheimer’s disease, contributing to Aβ aggregation and fibrillation that worsen this neuropathology. Nevertheless, the precise residues... more
Heavy metal ions and those of aluminum may interact with amyloid-β peptides (Αβ) associated with Alzheimer’s disease, contributing to Aβ aggregation and fibrillation that worsen this neuropathology. Nevertheless, the precise residues involved in metal ligation or interaction are yet to be established, although the N-terminal Aβ(1–16) peptide fragment is considered to be the metal-binding domain. However, because the results of the metal ion binding studies using Aβ(1–16) were not very conclusive, we have investigated shorter peptides. Here, we report the synthesis of truncated Aβ(9–16) peptide of the human Aβ(1–40) and Aβ(1–42) peptides, as well as its characterization by nuclear magnetic resonance and mass spectrometry. Furthermore, the Aβ(9–16) peptide interactions with various metal ions like Cu2+, Zn2+, Fe3+, Al3+, and Ni2+ were studied by circular dichroism, Fourier transform-infrared, and fluorescence spectroscopy. Our results show that the newly synthesized peptide sequence, which contains just two histidine and one tyrosine residues, seems to be a key site for metal binding, which was not thoroughly investigated so far. Light scattering spectra of Aβ(9–16) and its complexes with metal ions were measured, whereas some fluorescence experiments were also performed. Our data suggest that Aβ(9–16) peptide fragment coordination by metal ions is dependent on the type of metal, and the amino acid residues involved in metal bonding.Graphical Abstract