Search results for "lost"

Minireview: Recent progress in hemocyanin research

2011

This review summarizes recent highlights of our joint work on the structure, evolution, and function of a family of highly complex proteins, the hemocyanins. They are blue-pigmented oxygen carriers, occurring freely dissolved in the hemolymph of many arthropods and molluscs. They are copper type-3 proteins and bind one dioxygen molecule between two copper atoms in a side-on coordination. They possess between 6 and 160 oxygen-binding sites, and some of them display the highest molecular cooperativity observed in nature. The functional properties of hemocyanins can be convincingly described by either the Monod-Wyman-Changeux (MWC) model or its hierarchical extension, the Nested MWC model; the…

The role of water in hemoglobin function and stability

1993

Membrane Insertion of the Heptameric Staphylococcal α-Toxin Pore

2001

Abstract Staphylococcal α-toxin forms heptameric pores on eukaryotic cells. After binding to the cell membrane in its monomeric form, the toxin first assembles into a heptameric pre-pore. Subsequently, the pre-pore transforms into the final pore by membrane insertion of an amphipathic β-barrel, which comprises the “central loop” domains of all heptamer subunits. The process of membrane insertion was analyzed here using a set of functionally altered toxin mutants. The results show that insertion may be initiated within an individual protomer when its NH2 terminus activates its central loop. The activated state is then shared with the central loops of the residual heptamer subunits, which res…

Allosterically potentiating ligands of nicotinic receptors as a treatment strategy for Alzheimer's disease.

2000

Abstract One of the most prominent cholinergic deficit in Alzheimer’s disease (AD) is the reduced number of nicotinic acetylcholine receptors (nAChR) in the hippocampus and cortex of AD patients, as compared to age-matched controls. This deficit results in reduced nicotinic cholinergic excitation which may not only impair postsynaptic depolarization but also presynaptic neurotransmitter release and Ca 2+ -dependent intracellular signaling, including transcriptional activity. Presently, the most common approach to correct the nicotinic cholinergic deficit in AD is the application of cholinesterase inhibitors. Due to the resulting increase in synaptic acetylcholine levels, both in concentrati…

Chapter 8 Nicotinic receptors of the vertebrate CNS: introductory remarks

1996

Publisher Summary This chapter focuses on the nicotinic receptors of the vertebrate central nervous system (CNS). In vertebrates, nicotinic cholinergic neurotransmission is found in both the CNS and the periphery (muscle endplate). Although muscle and neuronal nicotinic acetylcholine receptors (nAChR) have evolved from a common ancestor, it is striking that the muscle receptor has remained rather stable in evolution, whereas the neuronal receptor has evolved to a wide diversity of subtypes. As an attractive hypothesis, neurotransmitters and neurohormones may not only interact with their archetypic cognate receptors but also with other neuroreceptor, albeit in a modulatory fashion. By modula…

A nonsense mutation abrogates production of a functional enterotoxin A in Clostridium difficile toxinotype VIII strains of serogroups F and X.

1999

Clostridium difficile strains of toxinotype VIII from serogroups F and X are described as toxin B-positive, toxin A-negative (TcdB+ A-), although they harbour almost the entire tcdA gene. To identify the reason for the lack of TcdA detection, we analyzed catalytic and ligand domains of TcdA-1470 of the type strain of serogroup F, strain 1470. Using recombinant fragments, the C-terminal immunodominant ligand domain TcdA3-1470, spanning amino acid residues 1694-2711 (corresponding to VPI 10463 sequence), was detected in Western blots. Similar experiments using the recombinant N-terminal catalytic fragment TcdAc1-2-1470 (amino acid positions 1-544) failed. In addition, this fragment showed no …

Emergence and Phylodynamics of Citrus tristeza virus in Sicily, Italy

2013

Citrus tristeza virus (CTV) outbreaks were detected in Sicily island, Italy for the first time in 2002. To gain insight into the evolutionary forces driving the emergence and phylogeography of these CTV populations, we determined and analyzed the nucleotide sequences of the p20 gene from 108 CTV isolates collected from 2002 to 2009. Bayesian phylogenetic analysis revealed that mild and severe CTV isolates belonging to five different clades (lineages) were introduced in Sicily in 2002. Phylogeographic analysis showed that four lineages co-circulated in the main citrus growing area located in Eastern Sicily. However, only one lineage (composed of mild isolates) spread to distant areas of Sici…

A compact linear Paul trap cooler buncher for CRIS

2020

A gas-filled linear Paul trap for the Collinear Resonance Ionisation Spectroscopy (CRIS) experiment at ISOLDE, CERN is currently under development. The trap is designed to accept beam from both ISOLDE target stations and the CRIS stable ion source. The motivation for the project along with the current design, simulations and future plans, will be outlined. peerReviewed

Reply to Z Weizman.

2013

Polycondensed nitrogen heterocycles. Part17. Isoxazolo[4,3-d]pyrazolo[3,4-f][1,2,3]triazepine. A new ring system

1987

The title compounds were prepared by nitration of compounds 2, reduction of the dinitro derivatives 4 and diazotization of the diamino derivatives 6 followed by an intramolecular coupling reaction. Compound 4a showed good activity against Salmonella cholerasuis and Clostridium perfringens bacteria.