A novel branched TAT(47-57) peptide for selective Ni(2+) introduction into the human fibrosarcoma cell nucleus

Zinc and iron dynamics in human islet amyloid polypeptide-induced diabetes mouse model

Metal homeostasis is tightly regulated in cells and organisms, and its disturbance is frequently observed in some diseases such as neurodegenerative diseases and metabolic disorders. Previous studies suggest that zinc and iron are necessary for the normal functions of pancreatic β cells. However, the distribution of elements in normal conditions and the pathophysiological significance of dysregulated elements in the islet in diabetic conditions have remained unclear. In this study, to investigate the dynamics of elements in the pancreatic islets of a diabetic mouse model expressing human islet amyloid polypeptide (hIAPP): hIAPP transgenic (hIAPP-Tg) mice, we performed imaging analysis of elements using synchrotron scanning X-ray fluorescence microscopy and quantitative analysis of elements using inductively coupled plasma mass spectrometry. We found that in the islets, zinc significantly decreased in the early stage of diabetes, while iron gradually decreased concurrently with the increase in blood glucose levels of hIAPP-Tg mice. Notably, when zinc and/or iron were decreased in the islets of hIAPP-Tg mice, dysregulation of glucose-stimulated mitochondrial respiration was observed. Our findings may contribute to clarifying the roles of zinc and iron in islet functions under pathophysiological diabetic conditions.

New Frontiers of Metallomics: Elemental and Species-Specific Analysis and Imaging of Single Cells

Single cells represent the basic building units of life, and thus their study is one the most important areas of research. However, classical analysis of biological cells eludes the investigation of cell-to-cell differences to obtain information about the intracellular distribution since it only provides information by averaging over a huge number of cells. For this reason, chemical analysis of single cells is an expanding area of research nowadays. In this context, metallomics research is going down to the single-cell level, where high-resolution high-sensitive analytical techniques are required. In this chapter, we present the latest developments and applications in the fields of single-cell inductively coupled plasma mass spectrometry (SC-ICP-MS), mass cytometry, laser ablation (LA)-ICP-MS, nanoscale secondary ion mass spectrometry (nanoSIMS), and synchrotron X-ray fluorescence microscopy (SXRF) for single-cell analysis. Moreover, the capabilities and limitations of the current analytical techniques to unravel single-cell metabolomics as well as future perspectives in this field will be discussed.

Armed by Asp? C-terminal carboxylate in a Dap-branched peptide and consequences in the binding of CuII and electrocatalytic water oxidation

C-Terminal carboxylate in branched peptide allows insight into water oxidation electrocatalysis by Cu-complexes, revealing differences to homologues with varied modules.

High yields and soluble expression of superoxide dismutases in Escherichia coli due to the HIV-1 Tat peptide via increases in mRNA transcription

This study aimed to validate the high yield and soluble expression of proteins carrying the transactivator of transcription (Tat) peptide tag, and further explored the potential mechanism by which the Tat tag increases expression. Escherichia coli superoxide dismutase (SOD) proteins, including SodA, SodB and SodC, were selected for analysis. As expected, the yields and the solubility of Tat-tagged proteins were higher than those of Tat-free proteins, and similar results were observed for the total SOD enzyme activity. Bacterial cells that overexpressed Tat-tagged proteins exhibited increased anti-paraquat activity compared with those expressing Tat-free proteins that manifested as SodA>SodC>SodB. When compared with an MG1655 wild-type strain, the growth of a ΔSodA mutant strain was found to be inhibited after paraquat treatment; the growth of ΔSodB and ΔSodC mutant strains was also slightly inhibited. The mRNA transcript level of genes encoding Tat-tagged proteins was higher than that of genes encoding Tat-free proteins. Furthermore, the α-helix and turn of Tat-tagged proteins were higher than those of Tat-free proteins, but the β-sheet and random coil content was lower. These results indicated that the incorporation of the Tat core peptide as a significant basic membrane transduction peptide in fusion proteins could increase mRNA transcripts and promote the high yield and soluble expression of heterologous proteins in E. coli.

Self-assembled, nanostructured coatings for water oxidation by alternating deposition of Cu-branched peptide electrocatalysts and polyelectrolytes

This work demonstrates the heterogenization of homogeneous water oxidation electrocatalysts in surface coatings produced by combining the substances with a suitable polyelectrolyte.

This work demonstrates the heterogenization of homogeneous water oxidation electrocatalysts in surface coatings produced by combining the substances with a suitable polyelectrolyte. The electrocatalysts i.e. Cu(ii)-branched peptide complexes involving a 2,3-l-diaminopropionic acid junction unit are heterogenized by building composite layers on indium-tin-oxide (ITO) electrode surface. Alternating deposition of the peptide complexes and poly(l-lysine) or poly(allylamine hydrochloride) were carried out in the presence of phosphate in a pH range of 7.5–10.5. Discussion of the results is divided to (1) characteristics of composite layer buildup and (2) electrocatalytic water oxidation and accompanying changes of these layers. For (1), optical waveguide lightmode spectroscopy (OWLS) has been applied to reveal the layer-by-layer formation of a Cu-ligand/polyelectrolyte/phosphate coating. The fabricated structures had a nanoporous topography (atomic force microscopy). As for (2), electrochemistry employing coated ITO substrates indicated improved water oxidation electrocatalysis vs. neat ITO and dependence of this improvement on the presence or absence of a histidine ligand in the deposited Cu(ii)-complexes equally, as observed in homogeneous systems. Electrochemical OWLS revealed changes in the coatings in operando, upon alternating positive–zero–positive etc. polarization: after some initial loss of the coating mass steady-state electrolysis was sustained by a compact and stable layer. According to X-ray photoelectron spectroscopy Cu remains in an N-donor ligand environment after electrolysis.

Branched peptide with three histidines for the promotion of CuII binding in a wide pH range – complementary potentiometric, spectroscopic and electrochemical studies

Triple-arm, His-rich branched peptide stabilizes 1 : 1 Cu^II complex forms by switching between N- and C-terminal His coordination upon changes in pH.