Search results for "Transferase"

Zur frage: Psoriasis vulgaris und Leber

1964

Der wiederholt geauserten Meinung einer Krankheitskorrelation zwischen Psoriasis vulgaris und Leber wird durch Bestimmung fur die Leberdiagnostik besonders geeigneter Enzyme (Glutaminsaure-Oxalessigsaure-Transaminase, Glutaminsaure-Brenztraubensaure-Transaminase, Aldolase) und des Zweifarbstofftests sowie wiederholt auch des Serumgesamtbilirubins nachgegangen. In der uberwiegenden Zahl der Psoriasis vulgaris-Kranken konnten normale Befunde erhoben werden. Von 14 Psoriatikern mit vorwiegend nur gering von der Norm abweichenden Befunden konnte anamnestisch und klinisch zumeist die Ursache fur die pathologischen Serum veranderungen ermittelt werden, ohne das sich jedoch hieraus der Nachweis fu…

MiR-221 promotes stemness of breast cancer cells by targeting DNMT3b

2016

// Giuseppina Roscigno 1, 2 , Cristina Quintavalle 1, 2 , Elvira Donnarumma 3 , Ilaria Puoti 1 , Angel Diaz-Lagares 4 , Margherita Iaboni 1 , Danilo Fiore 1 , Valentina Russo 1 , Matilde Todaro 5 , Giulia Romano 6 , Renato Thomas 7 , Giuseppina Cortino 7 , Miriam Gaggianesi 5 , Manel Esteller 4 , Carlo M. Croce 6 , Gerolama Condorelli 1, 2 1 Department of Molecular Medicine and Medical Biotechnology, “Federico II” University of Naples, Naples, Italy 2 IEOS-CNR, Naples, Italy 3 IRCCS-SDN, Naples, Italy 4 Epigenetic and Cancer Biology Program (PEBC) IDIBELL, Hospital Duran I Reynals, Barcelona, Spain 5 Department of Surgical and Oncological Sciences, Cellular and Molecular Pathophysiology Lab…

How To Design Selective Ligands for Highly Conserved Binding Sites: A Case Study Using N-Myristoyltransferases as a Model System

2019

A model system of two related enzymes with conserved binding sites, namely N-myristoyltransferase from two different organisms, was studied to decipher the driving forces that lead to selective inhibition in such cases. Using a combination of computational and experimental tools, two different selectivity-determining features were identified. For some ligands, a change in side-chain flexibility appears to be responsible for selective inhibition. Remarkably, this was observed for residues orienting their side chains away from the ligands. For other ligands, selectivity is caused by interfering with a water molecule that binds more strongly to the off-target than to the target. On the basis o…

Inhibition of the herpes simplex virus-coded thymidine kinase-complex by 9-?-D-arabinofuranosyladenine 5?-monophosphate (ara-AMP) and 9-(2-hydroxyeth…

1984

The thymidine kinase-complex isolated from herpes simplex virus type 1 and type 2 (HSV-1 and HSV-2) is associated with the following enzyme activities: ATP:dThd (dCyd) deoxypyrimidine kinase, ATP:dTMP thymidylate kinase, ADP:dThd- and AMP:dThd5′-phosphotransferase. In kinetic experiments it is shown that ara-AMP inhibits AMP:dThd- and ADP:dThd phosphotransferase activity, while acyclo-GMP impairs ADP:dThd phosphotransferase reaction only; the inhibition was found to be non-compertitive. The functional subunit ATP:dThd kinase was not affected by either compound.

Isolierung und charakterisierung einer cholinkinase aus Phaseolus vulgaris L.-Keimlingen

1977

Summary The enzyme choline kinase (ATP: Choline phosphotransferase E.C. 2.7.1.32) was extracted and partially purified from hypocotyl hooks of Phaseolus vulgaris L. seedlings. K m -value and pH-dependence of the activity were determined. The amount of enzyme activity in extracts depended on light conditions used for plant growth. Etiolated seedlings showed much lower enzyme levels than those grown in white light. Blue and red light conditions decreased enzyme levels below dark values. The in vitro enzyme activity was influenced by inhibitors and growth regulators. The enzyme activity was stimulated by Atropine, 2-Chloroethylammoniumchloride (Cycocel) and Gibberellic acid and was inhibited b…

RAS proteins and control of the cell cycle inSaccharomyces cerevisiae

1995

Genes related to the mammalian H-, K-, and N-ras oncogenes were identified in S. cerevisiae by DNA hybridization techniques (for reviews, see Tamanoi, 1988; Gibbs and Marshall, 1989; Broach and Deschenes, 1990). According to the rules of yeast genetics (dominant genes are indicated by three capital letters followed by a number), the yeast genes were denominated RAS1 and RAS2 (collectively referred to as RAS). The corresponding RAS1 and RAS2 proteins were 309 and 322 amino acids long, respectively. The sequence similarity between the human and yeast proteins was very high, reaching 90% identity at the level of the N-terminal 80 amino acids. As a consequence, perfect sequence conservation was…

2000

In eukaryotic cells, proteins are translocated across the ER membrane through a continuous ribosome-translocon channel. It is unclear to what extent proteins can fold already within the ribosome-translocon channel, and previous studies suggest that only a limited degree of folding (such as the formation of isolated α-helices) may be possible within the ribosome. We have previously shown that the conformation of nascent polypeptide chains in transit through the ribosome-translocon complex can be probed by measuring the number of residues required to span the distance between the ribosomal P-site and the lumenally disposed active site of the oligosaccharyl transferase enzyme (J. Biol. Chem 27…

N-glycosylation efficiency is determined by the distance to the C-terminus and the amino acid preceding an Asn-Ser-Thr sequon

2010

N-glycosylation is the most common and versatile protein modification. In eukaryotic cells, this modification is catalyzed cotranslationally by the enzyme oligosaccharyltransferase, which targets the β-amide of the asparagine in an Asn-Xaa-Ser/Thr consensus sequon (where Xaa is any amino acid but proline) in nascent proteins as they enter the endoplasmic reticulum. Because modification of the glycosylation acceptor site on membrane proteins occurs in a compartment-specific manner, the presence of glycosylation is used to indicate membrane protein topology. Moreover, glycosylation sites can be added to gain topological information. In this study, we explored the determinants of N-glycosylati…

Kinetic properties of a nucleoside phosphotransferase of chick embryo

1981

1. A nonspecific nucleoside phosphotransferase (nucleotide : 3'-deoxynucleotide 5'-phosphotransferase, EC 2.7.1.77), purified from chick embryos, catalyzes the transfer of phosphate ester from a nucleotide donor to a nucleoside acceptor. 2. The enzyme exhibits sigmoidal kinetics with respect to nucleoside monophosphate donors, but with respect to nucleoside di- or triphosphate donors and nucleoside acceptors hyperbolic kinetics were obtained. 3. The nucleoside phosphotransferase of chick embryo is unstable to heat and is protected from inactivation by a large number of nucleosides. 4. Nucleoside di- and triphosphates lower both the concentration of nucleoside monophosphates required for hal…

Enzymatic Formation of Raucaffricine, the Major Indole Alkaloid ofRauwolfia serpentinaCell-Suspension Cultures

1991

The major alkaloid from Rauwolfia serpentina cell-suspension cultures, the glucoalkaloid raucaffricine (2), was enzymatically formed from vomilenine (1) and UDPG in presence of microsomal-bound enzyme. This glucosyltransferase exhibits a relatively high substrate specificity with strong preference for 1 and UDPG. The apparent Km values for 1 and UDPG were 40 μM and 0.8 mM, respectively, for raucaffricine formation. Optimum transferase activity was observed at 50° and pH 6.3. The taxonomic distribution of this enzyme seems to be very limited because transferase can he exclusively detected in raucaffricine-producing plant cells.