scholarly journals Mechanism of Intrinsic Resistance to Vancomycin in Clostridium innocuum NCIB 10674

2004 ◽  
Vol 186 (11) ◽  
pp. 3415-3422 ◽  
Author(s):  
Véronique David ◽  
Bülent Bozdogan ◽  
Jean-Luc Mainardi ◽  
Raymond Legrand ◽  
Laurent Gutmann ◽  
...  
Keyword(s):  
Mass Spectrometry ◽  
High Pressure ◽  
Amino Group ◽  
Intrinsic Resistance ◽  
Chromosomal Fragment ◽  
High Affinity ◽  
C Terminus ◽  
Low Levels ◽  
Enterococcus Gallinarum ◽  
Level Resistance

ABSTRACT We have studied the basis for intrinsic resistance to low levels of vancomycin in Clostridium innocuum NCIB 10674 (MIC = 8 μg/ml). Analysis by high-pressure liquid chromatography (HPLC) and mass spectrometry of peptidoglycan nucleotide precursors pools revealed the presence of two types of UDP-MurNac-pentapeptide precursors constitutively produced, an UDP-MurNAc-pentapeptide with a serine at the C terminus which represented 93% of the pool and an UDP-MurNAc-pentapeptide with an alanine at the C terminus which represented the rest of the pool. C. innocuum cell wall muropeptides containing pentapeptide[Ser], either dialanine substituted on the epsilon amino group of lysine or not, were identified and represented about 10% of the monomers while only 1% of pentapeptide[d-Ala] monomers were found. The sequence of a 2,465-bp chromosomal fragment from C. innocuum was determined and revealed the presence of ddlc. innocuum and C. innocuum racemase genes putatively encoding homologues of d-Ala:d-X ligases and amino acid racemases, respectively. Analysis of the pool of precursors of Enterococcus faecalis JH2-2, containing cloned ddlc. innocuum and C. innocuum racemase genes showed in addition to the UDP-MurNAc-pentapeptide[d-Ala], the presence of an UDP-MurNAc-pentapeptide[d-Ser] precursor. However, the expression of low-level resistance to vancomycin was observed only when both genes were cloned in E. faecalis JH2-2 together with the vanXYc gene from Enterococcus gallinarum BM4174 which encodes a d,d-peptidase which eliminates preferentially the high affinity vancomycin UDP-MurNAc-pentapeptide [d-Ala] precursors produced by the host. We conclude that resistance to vancomycin in C. innocuum NCIB 10674 was related to the presence of the two chromosomal ddlc. innocuum and C. innocuum racemase genes allowing the synthesis of a peptidoglycan precursor terminating in serine with low affinity for vancomycin.

Preparation and properties of three analogues of [5-leucine]enkephalin, substrates for enzyme conversion studies

1985 ◽  
Vol 50 (6) ◽  
pp. 1329-1334
Author(s):  
Jaroslav Vičar ◽  
Linda Servítová ◽  
Martin Flegel ◽  
Karel Hauzer ◽  
Tomislav Barth
Keyword(s):  
High Pressure ◽  
Liquid Chromatography ◽  
Guinea Pig ◽  
Ion Exchange Chromatography ◽  
Exchange Chromatography ◽  
Guinea Pig Ileum ◽  
Opioid Activity ◽  
C Terminus ◽  
N Terminus ◽  
Fragment Condensation

Analogues of [5-Leu]enkephalin, prolonged by methionine on the N-terminus or, by lysine or methionine on the C-terminus were prepared by fragment condensation, purified by ion exchange chromatography or high-pressure liquid chromatography. The substances were characterised by their opioid activity in a test on guinea-pig ileum in comparison with the activity of [5-Leu]enkephalin.

scholarly journals Ethoxylated Butoxyethanol-BADGE Adducts—New Potential Migrants from Epoxy Resin Can Coating Material

Materials ◽  
2021 ◽  
Vol 14 (13) ◽  
pp. 3682
Author(s):  
Monika Beszterda ◽  
Małgorzata Kasperkowiak ◽  
Magdalena Frańska ◽  
Sandra Jęziołowska ◽  
Rafał Frański
Keyword(s):  
Mass Spectrometry ◽  
High Pressure ◽  
Liquid Chromatography ◽  
Epoxy Resin ◽  
Diglycidyl Ether ◽  
Ionization Mass ◽  
Coating Materials ◽  
Oxyethylene Unit ◽  
Bisphenol A Diglycidyl Ether ◽  
Product Ions

The acetonitrile extracts of can-coating materials have been analyzed by using high-pressure liquid chromatography/electrospray ionization-mass spectrometry (HPLC/ESI-MS). On the basis of detected ions [M + H]+, [M + NH4]+, [M + Na]+ and product ions, the ethoxylated butoxyethanol-bisphenol A diglycidyl ether adducts were identified in two of the analyzed extracts. Although the oxyethylene unit-containing compounds are widely used for the production of different kinds of materials, the ethoxylated species have not been earlier detected in epoxy resin can-coatings.

scholarly journals Mechanical force effect on the two-state equilibrium of the hyaluronan-binding domain of CD44 in cell rolling

2015 ◽  
Vol 112 (22) ◽  
pp. 6991-6996 ◽  
Author(s):  
Takashi Suzuki ◽  
Miho Suzuki ◽  
Shinji Ogino ◽  
Ryo Umemoto ◽  
Noritaka Nishida ◽  
...  
Keyword(s):  
Shear Stress ◽  
Conformational Change ◽  
Mechanical Force ◽  
Binding Domain ◽  
Terminal Region ◽  
Hematopoietic Progenitor Cell ◽  
High Shear ◽  
Cell Rolling ◽  
High Affinity ◽  
C Terminus

CD44 is the receptor for hyaluronan (HA) and mediates cell rolling under fluid shear stress. The HA-binding domain (HABD) of CD44 interconverts between a low-affinity, ordered (O) state and a high-affinity, partially disordered (PD) state, by the conformational change of the C-terminal region, which is connected to the plasma membrane. To examine the role of tensile force on CD44-mediated rolling, we used a cell-free rolling system, in which recombinant HABDs were attached to beads through a C-terminal or N-terminal tag. We found that the rolling behavior was stabilized only at high shear stress, when the HABD was attached through the C-terminal tag. In contrast, no difference was observed for the beads coated with HABD mutants that constitutively adopt either the O state or the PD state. Steered molecular dynamics simulations suggested that the force from the C terminus disrupts the interaction between the C-terminal region and the core of the domain, thus providing structural insights into how the mechanical force triggers the allosteric O-to-PD transition. Based on these results, we propose that the force applied from the C terminus enhances the HABD–HA interactions by inducing the conformational change to the high-affinity PD transition more rapidly, thereby enabling CD44 to mediate lymphocyte trafficking and hematopoietic progenitor cell homing under high-shear conditions.

scholarly journals Fast log P determination by ultra-high-pressure liquid chromatography coupled with UV and mass spectrometry detections

2009 ◽  
Vol 394 (7) ◽  
pp. 1919-1930 ◽  
Author(s):  
Yveline Henchoz ◽  
Davy Guillarme ◽  
Sophie Martel ◽  
Serge Rudaz ◽  
Jean-Luc Veuthey ◽  
...  
Keyword(s):  
Mass Spectrometry ◽  
High Pressure ◽  
Liquid Chromatography ◽  
High Pressure Liquid Chromatography ◽  
Log P ◽  
Ultra High Pressure

scholarly journals Isotopologue distributions of peptide product ions by tandem mass spectrometry: Quantitation of low levels of deuterium incorporation

2007 ◽  
Vol 367 (1) ◽  
pp. 40-48 ◽  
Author(s):  
Benlian Wang ◽  
Gang Sun ◽  
David R. Anderson ◽  
Minghong Jia ◽  
Stephen Previs ◽  
...  
Keyword(s):  
Mass Spectrometry ◽  
Tandem Mass Spectrometry ◽  
Tandem Mass ◽  
Deuterium Incorporation ◽  
Product Ions ◽  
Low Levels ◽  
Peptide Product

Two ubiquitin-like conjugation systems that mediate membrane formation during autophagy

2013 ◽  
Vol 55 ◽  
pp. 39-50 ◽  
Author(s):  
Hitoshi Nakatogawa
Keyword(s):  
Light Chain ◽  
Membrane Dynamics ◽  
The Other ◽  
Aminobutyric Acid ◽  
Amino Group ◽  
Autophagosome Formation ◽  
Acid Receptor ◽  
Receptor Associated Protein ◽  
Atg Proteins ◽  
C Terminus

In autophagy, the autophagosome, a transient organelle specialized for the sequestration and lysosomal or vacuolar transport of cellular constituents, is formed via unique membrane dynamics. This process requires concerted actions of a distinctive set of proteins named Atg (autophagy-related). Atg proteins include two ubiquitin-like proteins, Atg12 and Atg8 [LC3 (light-chain 3) and GABARAP (γ-aminobutyric acid receptor-associated protein) in mammals]. Sequential reactions by the E1 enzyme Atg7 and the E2 enzyme Atg10 conjugate Atg12 to the lysine residue in Atg5, and the resulting Atg12–Atg5 conjugate forms a complex with Atg16. On the other hand, Atg8 is first processed at the C-terminus by Atg4, which is related to ubiquitin-processing/deconjugating enzymes. Atg8 is then activated by Atg7 (shared with Atg12) and, via the E2 enzyme Atg3, finally conjugated to the amino group of the lipid PE (phosphatidylethanolamine). The Atg12–Atg5–Atg16 complex acts as an E3 enzyme for the conjugation reaction of Atg8; it enhances the E2 activity of Atg3 and specifies the site of Atg8–PE production to be autophagy-related membranes. Atg8–PE is suggested to be involved in autophagosome formation at multiple steps, including membrane expansion and closure. Moreover, Atg4 cleaves Atg8–PE to liberate Atg8 from membranes for reuse, and this reaction can also regulate autophagosome formation. Thus these two ubiquitin-like systems are intimately involved in driving the biogenesis of the autophagosomal membrane.

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