Search results for "metalloproteins"
showing 9 items of 19 documents
Theory of CaL2,3-edge XAS using a novel multichannel multiple-scattering method
2003
A new method for calculating X-ray absorption spectroscopy (XAS) at the L2,3 edges of Ca and transition metals is presented. It is based on the multichannel multiple-scattering theory by Natoli et al. [Phys. Rev. B, (1990), 42, 1944-1968] combined with the eigen-channel R-matrix formalism. Atomic multiplet-like effects, owing to the Coulomb interaction of photoelectrons and the 2p hole, are taken into account through a configuration interaction ansatz for the final-state wavefunction. The various multiplet states lead to a set of channels for the photoelectron wavefunction, which is calculated in multiple-scattering theory. The method is applied to Ca, an important element for biological ap…
Tarantula Hemocyanin Shows Phenoloxidase Activity
1998
An enzyme generally catalyzes one well defined reaction with high specificity and efficiency. We report here in contrast that the copper protein hemocyanin of the tarantula Eurypelma californicum exhibits two different functions. These occur at the same active site. While hemocyanin usually is an oxygen carrier, its function can be transformed totally to monophenoloxidase and o-diphenoloxidase activity after limited proteolysis with trypsin or chymotrypsin. N-acetyldopamine (NADA) is more effectively oxidized than L-dopa or dopamine. This irreversible functional switch of tarantula hemocyanin function is limited to the two subunits b and c of its seven subunit types. A conserved phenylalani…
Identification of a copper chaperone from tomato fruits infected with Botrytis cinerea by differential display
2003
Differential display was used to isolate tomato genes responding to fungal infection. Here we describe the isolation and characterization of a gene that is down-regulated in tomato fruits infected with the phytopathogen Botrytis cinerea. The cDNA identified encodes a protein that shares sequence similarity to the amino terminal region of CCH, a copper chaperone from Arabidopsis thaliana, that participates in intracellular copper homeostasis by delivering Cu to the secretory pathway. The fact that this newly characterized tomato gene, referred to as LeCCH (Lycopersicon esculentum copper chaperone), be differentially expressed after fungal infection, suggests an interesting relationship betwe…
Subunits composition and allosteric control in Carcinus aestuarii hemocyanin
1998
Carcinus aestuarii hemocyanin (Hc) exists in two aggregation forms at pH 7.5 and 20 mM Ca2+: 24S accounting for 90% of total hemocyanin and 16S accounting for 10%. Removal of metal cations by EDTA at neutral pH causes the complete dissociation of 24S hemocyanin into two different 16S. At pH 9.2, 24S hemocyanin dissociates into a pH stable 16S and a 5S component. The 5S component consists of three monomeric fractions named CaeSS1 (10%), CaeSS2 (50%) and CaeSS3 (40%); the latter fraction consisting of two isoforms. The fractions CaeSS1, CaeSS2 and CaeSS3 have been studied as far as their reassociation properties to form hexamers are concerned. We investigated the oxygen-binding properties of …
Towards peptide-based tunable multistate memristive materials
2021
Development of new memristive hardware is a technological requirement towards widespread neuromorphic computing. Molecular spintronics seems to be a fertile field for the design and preparation of this hardware. Within molecular spintronics, recent results on metallopeptides demonstrating the interaction between paramagnetic ions and the chirality induced spin selectivity effect hold particular promise for developing fast (ns–μs) operation times. [R. Torres-Cavanillas et al., J. Am. Chem. Soc., 2020, DOI: 10.1021/jacs.0c07531]. Among the challenges in the field, a major highlight is the difficulty in modelling the spin dynamics in these complex systems, but at the same time the use of inexp…
Focal adhesions are hotspots for keratin filament precursor formation
2006
Recent studies showed that keratin filament (KF) formation originates primarily from sites close to the actin-rich cell cortex. To further characterize these sites, we performed multicolor fluorescence imaging of living cells and found drastically increased KF assembly in regions of elevated actin turnover, i.e., in lamellipodia. Abundant KF precursors (KFPs) appeared within these areas at the distal tips of actin stress fibers, moving alongside the stress fibers until their integration into the peripheral KF network. The earliest KFPs were detected next to actin-anchoring focal adhesions (FAs) and were only seen after the establishment of FAs in emerging lamellipodia. Tight spatiotemporal …
Analysis of the Cellular Roles of MOCS3 Identifies a MOCS3-Independent Localization of NFS1 at the Tips of the Centrosome
2019
The deficiency of the molybdenum cofactor (Moco) is an autosomal recessive disease, which leads to the loss of activity of all molybdoenzymes in humans with sulfite oxidase being the essential protein. Moco deficiency generally results in death in early childhood. Moco is a sulfur-containing cofactor synthesized in the cytosol with the sulfur being provided by a sulfur relay system composed of the L-cysteine desulfurase NFS1, MOCS3, and MOCS2A. Human MOCS3 is a dual-function protein that was shown to play an important role in Moco biosynthesis and in the mcm(5)s(2) U thio modifications of nucleosides in cytosolic tRNAs for Lys, Gln, and Glu. In this study, we constructed a homozygous MOCS3 …
Bakteryjne strategie wykorzystania jonów metali – kulisy chemii koordynacyjnej
2022
n the Biological Inorganic Chemistry Group we are inspired to better understand metal ions acquisition and homeostasis in pathogenic bacteria, and in this review we present three different approaches to the role of these processes. The growing importance of a full understanding of the iron transport system in pathogens prompted us to study synthetic analogs of siderophores, used as structural probes in the process of iron uptake by microorganisms. The ferrichrome biomimetic analogs allowed efficient Fe(III) chelation under biological conditions and were recognized better by P. putida. than E. coli, suggesting differences in uptake mechanisms. Addition of a fluorescent probe to the compound …
Sponge‐Like Behaviour in Isoreticular Cu(Gly‐His‐X) Peptide‐Based Porous Materials
2015
We report two isoreticular 3D peptide-based porous frameworks formed by coordination of the tripeptides Gly-L-His-Gly and Gly-L-His-L-Lys to Cu(II) which display sponge-like behaviour. These porous materials undergo structural collapse upon evacuation that can be reversed by exposure to water vapour, which permits recovery of the original open channel structure. This is further confirmed by sorption studies that reveal that both solids exhibit selective sorption of H2 O while CO2 adsorption does not result in recovery of the original structures. We also show how the pendant aliphatic amine chains, present in the framework from the introduction of the lysine amino acid in the peptidic backbo…