Search results for "Histidine"

Impact of histidine spacing on modified polyhistidine tag – Metal ion interactions

2018

Abstract Histidine rich sequences are chosen both by nature and by molecular biologists due to their high affinity towards metal ions. In this work, we examine the affinity and binding modes of Cu 2+ , Ni 2+ and Zn 2+ towards two histidine tags, the common His 6 -tag (Ac-HHHHHH-NH 2 ) and its modified sequence, which also contains six histidines, but separated with two alanine residues (Ac-HAAHAAHAAHAAHAAHAA-NH 2 ). The spatial separation of histidines has an important impact on its coordination properties. Cu 2+ and Ni 2+ complexes with Ac-HHHHHH-NH 2 are more stable than those with Ac-HAAHAAHAAHAAHAAHAA-NH 2 ; the contrary is observed for Zn 2+ . In a narrow range of pH, Cu 2+ -Ac-HHHHHH-…

Paramagnetic NMR investigations of Co(II) and Ni(II) amicyanin.

1999

The paramagnetic 1H NMR spectra of the Co(II) and Ni(II) substituted forms of the type 1 blue copper protein (cupredoxin) amicyanin have been assigned. This is the first such analysis of a cupredoxin, which has a distorted tetrahedral active site with the ligands provided by two histidines, a cysteine and a methionine. The isotropic shifts of the resonances in these spectra are compared with those of Co(II) and Ni(II) azurin. A number of interesting similarities and differences are found. The coordination of the metal by the two equatorial histidine ligands is very similar in both proteins. The interaction between the introduced metal and the thiolate sulfur of the equatorial cysteine ligan…

CyaC, a redox-regulated adenylate cyclase of Sinorhizobium meliloti with a quinone responsive diheme-B membrane anchor domain.

2019

The nucleotide cyclase CyaC of Sinorhizobium meliloti is a member of class III adenylate cyclases (AC), a diverse group present in all forms of life. CyaC is membrane-integral by a hexahelical membrane domain (6TM) with the basic topology of mammalian ACs. The 6TM domain of CyaC contains a tetra-histidine signature that is universally present in the membrane anchors of bacterial diheme-B succinate-quinone oxidoreductases. Heterologous expression of cyaC imparted activity for cAMP formation from ATP to Escherichia coli, whereas guanylate cyclase activity was not detectable. Detergent solubilized and purified CyaC was a diheme-B protein and carried a binuclear iron-sulfur cluster. Single poin…

Structural analysis of copper(I) interaction with amyloid β peptide

2019

Abstract The N-terminal fragment of Aβ (β = beta) peptide is able to bind essential transition metal ions like, copper, zinc and iron. Metal binding usually occurs via the imidazole nitrogens of the three His residues which play a key role in the coordination chemistry. Among all the investigated systems, the interaction between copper and Amyloid β assume a biological relevance because of the interplay between the two copper oxidation states, Cu(II) and Cu(I), and their involvement in redox reactions. Both copper ions share the ability to bind Amyloid β. A huge number of investigations have demonstrated that Cu(II) anchors to the N-terminal amino and His6, His13/14 imidazole groups, while …

Compartmentalization of biosynthetic enzymes in bacterial cells: the histidine metabolic pathway case

Introduction: It is known that the inner concentration of proteins within the cell cytoplasm is so high that limits the diffusion of enzymes and metabolic intermediates, leading to a loss of time and energy. Therefore, the organization of genes in operons would have enabled to have enzymes involved in the same metabolic pathway physically close to each other. A corollary to this hypothesis in the possibility of physical interactions between the enzymes of the same metabolic pathway, resulting in the formation of a supramolecular complex capable in channeling the intermediates from one enzyme to a physical adjacent one, with restricted diffusion in the surrounding milieu. Objectives: The aim…

Purification and analysis of polyhistidine-tagged human parvovirus B19 VP1 and VP2 expressed in insect cells

2008

Human parvovirus B19 is an autonomously replicating human pathogen with a specific tropism for human erythroid progenitor cells. There is an interest in producing empty nucleocapsids of B19 as they can be used as tools in molecular biology and diagnostics. Native B19 virus particles are formed from two structural viral proteins, VP1 and VP2. The VP2 protein alone is able to self assemble and consequently form virus-like particles (VLPs) in heterologous expression systems. Purification of recombinant VLPs has been conducted using various traditional methods. These include laborious and time-consuming, e.g. cesium chloride or sucrose gradient ultracentrifugation steps, allowing limited workin…

Discrimination between Single Protein Conformations Using Dynamic SERS

2016

In biomedicine and biophysics, the discrimination of protein conformations is of critical importance for identifying the unfolding states in the diagnosis of neurodegenerative diseases. We develop a dynamic Raman spectroscopic approach based on a statistical analysis of the time series of spectral fingerprints of single protein. We show that the unfolded state of bovine serum albumin can be identified in the time series using the fluctuations of the Raman bands of some amino acids, tryptophan, tyrosine, leucine, and histidine, acting as biomarkers. The statistical analysis induces also the sorting between physisorption and chemisorption events. This is confirmed by the spectral analysis of …

Influence of metal ions on thermal aggregation of bovine serum albumin: aggregation kinetics and structural changes

2009

Metal ions are implicated in protein aggregation processes of several neurodegenerative pathologies. In this work the effects of Cu(II) and Zn(II) ions on heat-induced structural modifications of bovine serum albumin (BSA) were studied, with the aim of delineating the role of these ions in the early stages of proteins aggregation kinetics. A joint application of different techniques was used. The aggregate growth was followed by dynamic light scattering measurements, whereas the conformational changes occurring in the protein structure were monitored by Raman and IR spectroscopy. Both in absence and in presence of metal ions, heating treatment gave rise to b-structures to the detriment of a…

Effect of L-Histidine on the Survival of a T-Strain of Mycoplasma

1975

The addition of L-histidine to the growth medium prolongs the stationary phase and the survival of a T-strain of mycoplasma. Results of an experiment performed with 14 C-labeled urea demonstrate that the action of L-histidine is based on the retardation of the rise of pH.

Effects of vinblastine, leucine, and histidine, and 3-methyladenine on autophagy in Ehrlich ascites cells.

1990

The microtubule inhibitor vinblastine causes accumulation of autophagic vacuoles in many cell types. In hepatocytes, many of the accumulated vacuoles are nascent, which has been interpreted to suggest that vinblastine acts by inhibiting the fusion of hydrolase-containing lysosomes with early autophagic vacuoles. However, our previous results suggested that, in Ehrlich ascites cells, vinblastine causes accumulation mainly of older autophagic vacuoles (AVs). This study was undertaken to further characterize the mode of action of vinblastine in these cells. The vinblastine-accumulated AVs were quantified by electron-microscopic morphometry. In addition, the effects of inhibitors of autophagic …