Search results for " Amin"
showing 10 items of 944 documents
Short hydrogen bonds enhance nonaromatic protein-related fluorescence
2021
Significance Intrinsic fluorescence of nonaromatic amino acids is a puzzling phenomenon with an enormous potential in biophotonic applications. The physical origins of this effect, however, remain elusive. Herein, we demonstrate how specific hydrogen bond networks can modulate fluorescence. We highlight the key role played by short hydrogen bonds, present in the protein structure, on the ensuing fluorescence. We provide detailed experimental and molecular evidence to explain these unusual nonaromatic optical properties. Our findings should benefit the design of novel optically active biomaterials for applications in biosensing and imaging.
Nephrotoxic and hepatotoxic effects of chromium compounds in rats
1986
The nephrotoxic, hepatotoxic and cardiotoxic actions of hexavalent chromium compounds, as well as their effects on lung, blood and circulation may contribute to the fatal outcome of chromium intoxication. Although trivalent chromium have been regarded as relatively biologically inert, there are a few salts of chromium III that have been found to be carcinogenic when inhaled, ingested or brought in contact with the tissues. Sensitive persons and industry workers have been subjects of dermatitis, respiratory tract injuries and digestive ulcers due to chromium compounds. In this work, the authors have studied the effect of trivalent and hexavalent chromium compounds on rats measuring the trans…
Biopartitioning micellar chromatography to pedict mutagenicity of aromatic amines
2007
[EN] Mutagenicity is a toxicity endpoint associated with the chronic exposure to chemicals. Aromatic amines have considerable industrial and environmental importance due to their widespread use in industry and their mutagenic capacity. Biopartitioning micellar chromatography (BMC), a mode of micellar liquid chromatography that uses micellar mobile phases of Brij35 in adequate experimental conditions, has demonstrated to be useful in mimicking the drug partitioning process into biological systems. In this paper, the usefulness of BMC for predicting mutagenicity of aromatic amines is demonstrated. A multiple linear regression (MLR) model based on BMC retention data is proposed and compared wi…
Thiourea Organocatalysts as Emerging Chiral Pollutants: En Route to Porphyrin-Based (Chir)Optical Sensing
2021
Environmental pollution with chiral organic compounds is an emerging problem requiring innovative sensing methods. Amino-functionalized thioureas, such as 2-(dimethylamino)cyclohexyl-(3,5-bis(trifluoromethyl)phenyl)thiourea (Takemoto’s catalyst), are widely used organocatalysts with virtually unknown environmental safety data. Ecotoxicity studies based on the Vibrio fischeri luminescence inhibition test reveal significant toxicity of Takemoto’s catalyst (EC50 = 7.9 mg/L) and its NH2-substituted analog (EC50 = 7.2–7.4 mg/L). The observed toxic effect was pronounced by the influence of the trifluoromethyl moiety. En route to the porphyrin-based chemosensing of Takemoto-type thioureas, their s…
Determination of queuosine derivatives by reverse-phase liquid chromatography for the hypomodification study of Q-bearing tRNAs from various mammal l…
2004
Three queuosine derivatives (Q-derivatives) have been found at position 34 of four mammalian so-called Q-tRNAs: queuosine (Q) in tRNA(Asn) and tRNA(His), mannosyl-queuosine (manQ) in tRNA(Asp), and galactosyl-queuosine (galQ) in tRNA(Tyr). An analytical procedure based on the combined means of purified tRNA isolation from liver cells and ribonucleoside analysis by reverse-phase high performance liquid chromatography coupled with real-time UV-spectrometry (RPLC-UV) was developed for the quantitative analysis of the three Q-derivatives present in total tRNA from liver tissues and liver cell cultures. Using this analytical procedure, the rates of Q-tRNA modification were studied in total tRNAs…
Sequencing and analysis of the gene encoding the α-toxin of Clostridium novyi proves its homology to toxins A and B of Clostridium difficile
1995
A library of total Clostridium novyi DNA was established and screened for the alpha-toxin gene (tcn alpha) by hybridization with oligonucleotides derived from a partial N-terminal sequence and by using specific antisera. Overlapping subgenic tcn alpha fragments were isolated and subsequently the total sequence of tcn alpha was determined. The 6534 nucleotide open reading frame encodes a polypeptide of M(r) 250,166 and pI 5.9. The N-terminal alpha-toxin (Tcn alpha) sequence MLITREQLMKIASIP determined by Edman degradation confirmed the identity of the reading frame and the assignment of the translation start point. The toxin is not modified posttranslationally at its N-terminus nor does it co…
Characterization of a Novel Type of Serine/Threonine Kinase That Specifically Phosphorylates the Human Goodpasture Antigen
1999
Goodpasture disease is an autoimmune disorder that occurs naturally only in humans. Also exclusive to humans is the phosphorylation process that targets the unique N-terminal region of the Goodpasture antigen. Here we report the molecular cloning of GPBP (Goodpasture antigen-binding protein), a previously unknown 624-residue polypeptide. Although the predicted sequence does not meet the conventional structural requirements for a protein kinase, its recombinant counterpart specifically binds to and phosphorylates the exclusive N-terminal region of the human Goodpasture antigen in vitro. This novel kinase is widely expressed in human tissues but shows preferential expression in the histologic…
Complessi di Organostagno(IV) con amminoacidi e dipeptidi: sintesi, caratterizzazione e attività biologica in vitro.
2008
Scopo della ricerca è la sintesi, caratterizzazione strutturale ed attività biologica di complessi di organostagno(IV) e amminoacidi quali L-arginina (Arg), N-Boc-L-arginina (Boc-Arg), L-ornitina (L-Orn) ed un dipeptide contenente L-arginina, Alanil-Arginina (Ala-Arg). I complessi di diorganostagno(IV) sono noti possedere attività antitumorale [1], antimicrobica [2] e antiinfiammatoria. I complessi di triorganostagno(IV) inibiscono la funzione mitocondriale almeno in tre modi: 1) reagendo con le membrane cellulari; 2) alterando lo scambio Cl-/OH- attraverso la membrana; 3) inibendo la fosforilazione ossidativa o l’idrolisi di ATP [3].L’arginina (Arg) è un amminoacido essenziale con un grup…
Protein data condensation for effective quaternary structure classification
2007
Many proteins are composed of two or more subunits, each associated with different polypeptide chains. The number and the arrangement of subunits forming a protein are referred to as quaternary structure. The quaternary structure of a protein is important, since it characterizes the biological function of the protein when it is involved in specific biological processes. Unfortunately, quaternary structures are not trivially deducible from protein amino acid sequences. In this work, we propose a protein quaternary structure classification method exploiting the functional domain composition of proteins. It is based on a nearest neighbor condensation technique in order to reduce both the porti…
Properties of trialkylamines as catalysts of resoles synthesis
2000
A series of the syntheses of phenol–formaldehyde resoles was carried out in the presence of trimethyl-, triethyl-, tripropyl-, and tributylamines and sodium hydroxide as catalysts for this process. The rate constants were calculated for the partial reactions identified in the synthesis. Also, the performance properties of the resins obtained and the hardened resin samples were estimated in simple tests. © 2000 John Wiley & Sons, Inc. J Appl Polym Sci 77: 898–902, 2000