Search results for "AMINO ACID"

Purification and partial characterization of aminopeptidase from barley (Hordeum vulgare L.) seeds.

2013

Aminopeptidases (EC 3.4.11) are proteolytic enzymes, which hydrolyze one amino acid from N-terminus of peptidic substrates. Inhibitors of plant aminopeptidases can find an application in agriculture as herbicides. Isolation and partial characterization of aminopeptidase from barley (Hordeum vulgare L.) seeds has been described. The enzyme was purified to molecular homogeneity using a six-step purification procedure (precipitation with (NH4)2SO4, followed by chromatography on Sephadex G-25, DEAE-Sepharose, Sephacryl HR 300, Macro-Prep Q and Phenyl-Sepharose HP columns). The enzyme was purified 365-fold with recovery above 18%. The molecular weight of the purified enzyme was determined by SDS…

Pyrazole amino acids: hydrogen bonding directed conformations of 3-amino-1H-pyrazole-5-carboxylic acid residue

2017

A series of model compounds containing 3-amino-1H-pyrazole-5-carboxylic acid residue with N-terminal amide/urethane and C-terminal amide/hydrazide/ester groups were investigated by using NMR, Fourier transform infrared, and single-crystal X-ray diffraction methods, additionally supported by theoretical calculations. The studies demonstrate that the most preferred is the extended conformation with torsion angles ϕ and ψ close to ±180°. The studied 1H-pyrazole with N-terminal amide/urethane and C-terminal amide/hydrazide groups solely adopts this energetically favored conformation confirming rigidity of that structural motif. However, when the C-terminal ester group is present, the second con…

Steroidal derivatives of nitrogen containing compounds as potential gelators

2013

Redox reaction between amino‐(3,4‐dihydroxyphenyl)methyl phosphonic acid and dopaquinone is responsible for the apparent inhibitory effect on tyrosin…

2002

Amino‐(3,4‐dihydroxyphenyl)methyl phosphonic acid, the phosphonic analog of 3,4‐dihydroxyphenylglycine, had been previously reported as a potent inhibitor of tyrosinase. The mechanism of the apparent enzyme inhibition by this compound has now been established. Amino‐(3,4‐dihydroxyphenyl)methyl phosphonic acid turned out to be a substrate and was oxidized to o‐quinone, which evolved to a final product identified as 3,4‐dihydroxybenzaldehyde, the same as for 3,4‐dihydroxyphenylglycine. Monohydroxylated compounds (amino‐(3‐hydroxyphenyl)methyl phosphonic acid and amino‐(4‐hydroxyphenyl)methyl phosphonic acid) were not oxidized, neither was 4‐hydroxy‐l‐phenylglycine. However, the relatively hig…

RAB18 Loss Interferes With Lipid Droplet Catabolism and Provokes Autophagy Network Adaptations

2020

Autophagy is dependent on appropriate lipid supply for autophagosome formation. The regulation of lipid acquisition and the autophagy network response to lipid-limiting conditions are mostly elusive. Here, we show that the knockout of the RAB GTPase RAB18 interferes with lipid droplet catabolism, causing an impaired fatty acid release. The resulting reduced lipid-droplet-derived lipid availability influences autophagy and provokes adaptive modifications of the autophagy network. These adjustments include increased expression and phosphorylation of ATG2B as well as augmented formation of the ATG12-ATG5 conjugate. Moreover, ATG9A shows an enhanced phosphorylation at amino acid residues tyrosi…

Inhibition of Rac1 signaling by lovastatin protects against anthracycline-induced cardiac toxicity

2011

Normal tissue damage limits the efficacy of anticancer therapy. For anthracyclines, the clinically most relevant adverse effect is cardiotoxicity. The mechanisms involved are poorly understood and putative cardioprotectants are controversially discussed. Here, we show that the lipid-lowering drug lovastatin protects rat H9c2 cardiomyoblasts from doxorubicin in vitro. Protection by lovastatin is related to inhibition of the Ras-homologous GTPase Rac1. It rests on a reduced formation of DNA double-strand breaks, resulting from the inhibition of topoisomerase II by doxorubicin. Doxorubicin transport and reactive oxygen species are not involved. Protection by lovastatin was confirmed in vivo. I…

Dietary fatty acids in the retina: beyond DHA, is EPA the underestimate intermediate?

2016

Dietary fatty acids in the retina: beyond DHA, is EPA the underestimate intermediate?. 12. congress of the international society for the study of fatty acids and lipids

Cytotoxic necrotizing factor type 2 produced by virulent Escherichia coli modifies the small GTP-binding proteins Rho involved in assembly of actin s…

1994

Cytotoxic necrotizing factor type 2 (CNF2) produced by Escherichia coli strains isolated from intestinal and extraintestinal infections is a dermonecrotic toxin of 110 kDa. We cloned the CNF2 gene from a large plasmid carried by an Escherichia coli strain isolated from a lamb with septicemia. Hydropathy analysis of the deduced amino acid sequence revealed a largely hydrophilic protein with two potential hydrophobic transmembrane domains. The N-terminal half of CNF2 showed striking homology (27% identity and 80% conserved residues) to the N-terminal portion of Pasteurella multocida toxin. Methylamine protection experiments and immunofluorescence studies suggested that CNF2 enters the cytosol…

Activation of astroglial phospholipase D activity by phorbol ester involves ARF and Rho proteins.

2000

Primary cultures of rat cortical astrocytes express phospholipase D (PLD) isoforms 1 and 2 as determined by RT-PCR and Western blot. Basal PLD activity was strongly (10-fold) increased by 4beta-phorbol-12beta,13alpha-dibutyrate (PDB) (EC(50): 56 nM), an effect which was inhibited by Ro 31-8220 (0.1-1 microM), an inhibitor of protein kinase C (PKC), and by brefeldin A (10-100 microg/ml), an inhibitor of ADP-ribosylating factor (ARF) activation. Pretreatment of the cultures with Clostridium difficile toxin B-10463 (0.1-1 ng/ml), which inactivates small G proteins of the Rho family, led to a breakdown of the astroglial cytoskeleton; concomitantly, PLD activation by PDB was reduced by up to 50%…

Metabotropic glutamate receptors activate phospholipase D in astrocytes through a protein kinase C-dependent and Rho-independent pathway.

2003

Metabotropic glutamate receptors (mGluRs) are G protein-coupled receptors that mediate phospholipase D (PLD) activation in brain, but the mechanism underlying this response remains unclear. Here we used primary cultures of astrocytes as a cell model to explore the mechanism that links mGluRs to PLD. Glutamate activated both phospholipase C (PLC) and PLD with equal potency and this effect was mimicked by L-cysteinesulfinic acid, a putative neurotransmitter previously shown to activate mGluRs coupled to PLD, but not PLC, in adult brain. PLD activation by glutamate was dependent on Ca(2+) mobilization and fully blocked by both protein kinase C (PKC) inhibitors and PKC down-regulation, suggesti…