Search results for "binding"

Killer toxin of Hanseniaspora uvarum

1990

The yeast Hanseniaspora uvarum liberates a killer toxin lethal to sensitive strains of the species Saccharomyces cerevisiae. Secretion of this killer toxin was inhibited by tunicamycin, an inhibitor of N-glycosylation, although the mature killer protein did not show any detectable carbohydrate structures. Culture supernatants of the killer strain were concentrated by ultrafiltration and the extracellular killer toxin was precipitated with ethanol and purified by ion exchange chromatography. SDS-PAGE of the electrophoretically homogenous killer protein indicated an apparent molecular mass of 18,000. Additional investigations of the primary toxin binding sites within the cell wall of sensitiv…

Probing suggested catalytic domains of glycosyltransferases by site-directed mutagenesis.

2003

The plant enzyme arbutin synthase isolated from cell suspension cultures of Rauvolfia serpentina and heterologously expressed in Escherichia coli is a member of the NRD1beta family of glycosyltransferases. This enzyme was used to prove, by site-directed mutagenesis, suggested catalytic domains and reaction mechanisms proposed for enzyme-catalyzed glycosylation. Replacement of amino acids far from the NRD domain do not significantly affect arbutin synthase activity. Exchange of amino acids at the NRD site leads to a decrease of enzymatic activity, e.g. substitution of Glu368 by Asp. Glu368, which is a conserved amino acid in glycosyltransferases located at position 2 and is important for enz…

The dissociation channels of silver clusters Agn+, 3 ≤ n ≤ 20

1996

Abstract The low energy dissociation channels of silver cluster ions Agn+, 3 ≤ n ≤ 20 are determined by collision-induced dissociation (CID) in a Penning trap. While for most cluster sizes the first fragment cluster ion is produced by monomer evaporation, the fragment ion of small odd-sized clusters has two atoms less than their precursors indicating an evaporation of dimers. The results are compared to similar CID studies on gold cluster ions, photofragmentation patterns, abundance spectra for various silver-cluster production techniques and calculated binding energies.

Fragmentation pattern of gold clusters collided with xenon atoms

1994

Abstract The dissociation channels of gold cluster ions Au n + (2 ≤ n ≤ 23) have been investigated via collision induced dissociation in a Penning trap. Excited odd cluster ions with n ≤ 15 decay by evaporation of dimers, all others decay by monomer evaporation. Information on the binding energies is deduced from these dissociation channels.

Suppression of allograft rejection in the sponge Suberites domuncula by FK506 and expression of genes encoding FK506-binding proteins in allografts.

2001

SUMMARY Porifera (sponges) are, evolutionarily, the oldest metazoan phylum. Recent molecular data suggest that these animals possess molecules similar to and homologous with those of the innate and adaptive immune systems of higher Metazoa. Applying the biological system of parabiosis and the technique of differential display of mRNA, two cDNAs encoding putative FK506-binding proteins were isolated. FK506 is successfully used in clinics as a drug to prevent allograft rejection and is toxic to Suberites domuncula cells in vitro at doses above 100ng ml−1. Autograft fusion of transplants from S. domuncula was not affected by FK506. Allograft non-fusion was not affected by FK506 at toxic doses;…

Pharmacogenetic considerations for optimizing tacrolimus dosing in liver and kidney transplant patients

2013

The introduction of tacrolimus in clinical practice has improved patient survival after organ transplant. However, despite the long use of tacrolimus in clinical practice, the best way to use this agent is still a matter of intense debate. The start of the genomic era has generated new research areas, such as pharmacogenetics, which studies the variability of drug response in relation to the genetic factors involved in the processes responsible for the pharmacokinetics and/or the action mechanism of a drug in the body. This variability seems to be correlated with the presence of genetic polymorphisms. Genotyping is an attractive option especially for the initiation of the dosing of tacrolim…

2015

Bacterial infections remain a serious health concern, in particular causing life-threatening infections of hospitalized and immunocompromised patients. The situation is exacerbated by the rise in antibacterial drug resistance, and new treatments are urgently sought. In this endeavour, accurate structures of molecular targets can support early-stage drug discovery. Here, crystal structures, in three distinct forms, of recombinantPseudomonas aeruginosaβ-ketoacyl-(acyl-carrier-protein) synthase II (FabF) are presented. This enzyme, which is involved in fatty-acid biosynthesis, has been validated by genetic and chemical means as an antibiotic target in Gram-positive bacteria and represents a po…

Isolation of carcinoembryonic antigen N-terminal domains (N-A1) from soluble aggregates

2011

Abstract Carcinoembryonic antigen (CEA) was identified as a prominent tumor-associated antigen in human colorectal cancer and it is still intensively investigated. However, its physiological role remains unclear. The CEA molecule is composed of seven highly hydrophobic, immunoglobulin-like domains, six of which contain a single disulphide bridge. The production of recombinant protein containing Ig-like domains in bacterial expression systems often results in partial degradation or insolubility due to aggregation hampering the analysis of their native structure and function. Here, we present a new method of expression and purification of CEA N-terminal domains (N-A1) fused to MBP in Escheric…

Modulation of base excision repair of 8-oxoguanine by the nucleotide sequence.

2013

8-Oxoguanine (8-oxoG) is a major product of oxidative DNA damage, which induces replication errors and interferes with transcription. By varying the position of single 8-oxoG in a functional gene and manipulating the nucleotide sequence surrounding the lesion, we found that the degree of transcriptional inhibition is independent of the distance from the transcription start or the localization within the transcribed or the non-transcribed DNA strand. However, it is strongly dependent on the sequence context and also proportional to cellular expression of 8-oxoguanine DNA glycosylase (OGG1)-demonstrating that transcriptional arrest does not take place at unrepaired 8-oxoG and proving a causal…

8-Oxo-7,8-dihydroguanine in DNA does not constitute a barrier to transcription, but is converted into transcription-blocking damage by OGG1.

2011

The common DNA base modification 8-oxo-7,8-dihydroguanine (8-oxo-G) affects the efficiency and fidelity of transcription. We constructed plasmid substrates carrying single 8-oxo-G residues, specifically positioned in the transcribed or the non-transcribed DNA strands, to investigate their effects on the expression of an EGFP reporter gene and to explore the role of base excision repair in the mechanism of transcription inhibition. We report that 8-oxo-G does not directly block transcription in cells, since a single 8-oxo-G in the transcribed DNA strand did not reduce the EGFP expression levels in repair-deficient (OGG1-null) mouse embryonic fibroblast cell lines. Rather, inhibition of trans…