Medical transfer

Many biological C-H activation reactions exhibit nonclassical kinetic isotope effects (KIEs). These nonclassical KIEs are too large (kH/kD 7) and/or exhibit unusual temperature dependence such that the Arrhenius prefactor KIEs (AH/AD) fall outside of the semiclassical range near unity. The focus of this minireview is to discuss such KIEs within the context of the environmentally coupled hydrogen tunneling model.

9p system191 01-06-2013 37 4   Download

Mucopolysaccharidosis type I (MPS I) results from a deficiency in the enzyme a-L-iduronidase (IDUA), and is characterized by skeletal abnormalities, hepatosplenomegaly and neurological dysfunction. In this study, we used a late generation lentiviral vector to evaluate the utility of this vector system for the transfer and expression of the human IDUA cDNA in MPS I fibroblasts. We observed that the level of enzyme expression in transduced cells was 1.5-fold the level found in normal cells; the expression persisted for at least two months....

8p system191 01-06-2013 31 5   Download

The ¯uorescence resonance energy transfer parameter, f, is de®ned as the eciency of the energy transfer normalized by the quantum yield of the donor in the presence of acceptor. It is possible to characterize the ¯exibility of the protein matrix between the appropriate ¯uorescent probes by monitoring the temperature dependence of f. The intermonomer ¯exibility of the Ca-actin and Mg-actin ®laments was characterized by using this method at pH values of 6.5 and 7.4.

8p research12 01-06-2013 53 4   Download

The functional replacement of the primary ubiquinone (QA) in the photosynthetic reaction center (RC) from Rhodo-bacter sphaeroideswith synthetic vitamin K derivatives has provided a powerful tool to investigate the electron transfer mechanism. To investigate the binding mode of these qui-nones to theQAbinding sitewe have determined the binding free energy and charge recombination rate from QA ± to D + (kAD) of 29 different 1,4-naphthoquinone derivatives with systematically altered structures.

13p research12 01-06-2013 51 4   Download

Two modi®cations of 5-acetimidoylamino-7-acetamido-3,5,7,9-tetradeoxy-D-glycero-D-galacto-non-2-ulosonic acid (5-N-acetimidoyl-7-N-acetyllegionaminic acid) in the O-chainpolysaccharide (OPS) of theLegionellapneumophila serogroup 1 lipopolysaccharide (LPS) concern N-methyla-tionof the 5-N-acetimidoyl group in legionaminic acid. Both N-methylated substituents, the (N,N-dimethylacetimidoyl) amino and acetimidoyl(N-methyl)amino group, could be allocated to one single legionaminic acid residue in the long-and middle-chain OPS, respectively. ...

10p research12 23-04-2013 27 2   Download

Special oligonucleotides for targeted gene correction have attracted increasing attention recently, one of which is the chimericRNAÆDNAoligonucleotide (RDO) system. RDOs for targeted gene correction were first designed in 1996, and are typically 68 nucleotides in length including continuous RNA andDNA sequences (RNA is 2¢-O-methyl-modified).

6p tumor12 22-04-2013 34 2   Download

One-electron oxidation of six different c-type lysozymes from hen egg white, turkey egg white, human milk, horse milk, camel stomach and tortoise was studied by gamma-and pulse-radiolysis.In the first step, one tryptophan side chain is oxidized to indolyl free radical, which is produced quantitatively.As shown already, the indolyl radical subse-quently oxidizes a tyrosine side chain to the phenoxy radical in an intramolecular reaction.However this reaction is not total and its stoichiometry depends on the protein.Rate constants also vary between proteins, from 120Æs )1 to 1000Æs )1 at pH 7.

7p tumor12 20-04-2013 40 2   Download

The role of coenzyme binding in regulating interflavin electron transfer in human cytochrome P450 reductase (CPR) has been studied using temperature-jump spectros-copy. Previous studies [Gutierrez, A., Paine, M., Wolf, C.R., Scrutton, N.S., & Roberts, G.C.K.Biochemistry (2002) 41,4626–4637] have shown that the observed rate, 1/s, of interflavin electron transfer (FADsq )FMNsq fi FADox)FMNhq) inCPRreduced at the two-electron level with NADPH is 55 ± 2 s )1 , whereas with dithionite-reduced enzyme the observed rate is 11 ± 0.

10p fptmusic 16-04-2013 34 4   Download

The roles of His181, His184 and Tyr186 in PETN reductase have been examined by mutagenesis, spectroscopic and stopped-flow kinetics, and by determination of crystallographic structures for the Y186F PETN reductase and reduced wild-type enzyme—progesterone complex. Residues His181 and His184 are important in the binding of coenzyme, steroids, nitro-aromatic ligands and the substrate 2-cyclohexen-1-one.

12p fptmusic 12-04-2013 40 3   Download

A new baculovirus-based fluorescence resonance energy transfer (Bv-FRET) assay for measuringmultimerization of cell surface molecules in living cells is described. It has been demonstrated that gonadotropin-releasing hormone recep-tor (GnRH-R) was capable of forming oligomeric com-plexes in the plasma membrane under normal physiological conditions. The mouse gonadotropin-releasing hormone receptor GnRH-R was used to evaluate the efficiency and potential applications of this assay.

9p fptmusic 12-04-2013 58 4   Download

Ultrasensitive responses are common in cellular information transfer because they allow cells to decode extracellular stimuli in an all-or-none manner. Biochemical responses are usually analyzed by fitting the Hill equation, and the estimated Hill coefficient is taken as a measure of sensi-tivity. However, this approach is not appropriate if the response under con-sideration significantly deviates from the best-fit Hill equation.

9p fptmusic 11-04-2013 30 2   Download

A wide range of approaches has been applied to examine the quaternary structure of G protein-coupled receptors, the basis of such protein–protein interactions and how such interactions might modulate the pharmacology and function of these receptors. These include coimmunoprecipitation, var-ious adaptations of resonance energy transfer techniques, functional com-plementation studies and the analysis of ligand-binding data.

12p fptmusic 11-04-2013 50 3   Download

Transcription of yeast phospholipid biosynthesis structural genes, which contain an inositol-sensitive upstream activa-ting sequence in their promoters, responds to the availability of the soluble precursors inositol and choline and to changes in phospholipid metabolism.

8p awards 05-04-2013 39 3   Download

3,3¢-Dipropyl-2,2¢-thiadicarbocyanine iodide [DiS-C3 (5)], often used as a tracer dye to assess the mitochondrial mem-brane potential, was investigated in detail regarding its effects on the structure and function of isolated mitochon-dria. As reported previously, DiS-C3(5) had an inhibitory effect on NADH-driven mitochondrial electron transfer. On the contrary, in the presence of inorganic phosphate, DiS-C3(5) showed dose-dependent biphasic effects on mito-chondria energized by succinate. At higher concentrations, such as 50lM,DiS-C3(5) acceleratedmitochondrial oxygen consumption. ...

0p awards 05-04-2013 35 2   Download

To test thioredoxin resistance to oxidizing free radicals, we have studied the one-electron oxidation of wild-type thio-redoxin and of two forms with the point mutations D30A and W35A, using azide radicals generated byc-ray or pulse radiolysis. The oxidation patterns of wild-type thioredoxin and D30A are similar. In these forms, Trp35 is the primary target and is
repaired by one-electron reduction; first by intramolecular electron transfer from tyrosine, and then fromother residues. Conversely, duringoxidationofW35A, Trp13 is poorly reactive.

7p awards 05-04-2013 37 4   Download

The amino acid residue tryptophan 27 of 6,7-dimethyl-8-ribityllumazine synthase of the yeastSchizosaccharomyces pombewas replacedby tyrosine. The structures of theW27Y mutant protein in complex with riboflavin, the substrate analogue 5-nitroso-6-ribitylamino-2,4(1H,3H)-pyrimidin-edione, and the product analogue 6-carboxyethyl-7-oxo-8-ribityllumazine,weredeterminedbyX-raycrystallography at resolutions of 2.7–2.8 A ˚ .

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UDP-N-acetylglucosamineenolpyruvyl transferase (MurA), catalyzes the first step in the biosynthesis of peptidoglycan, involving the transfer of the intactenolpyruvyl moiety from phosphoenolpyruvate to the 3¢-hydroxyl group of UDP-N-acetylglucosamine (UDPNAG). The enzyme is irreversibly inhibited by the antibiotic fosfomycin. The inactivation is caused by alkylation of a highly conserved cysteine residue (C115) that participates in the binding of phos-phoenolpyruvate.

9p dell39 03-04-2013 52 4   Download

Inorder to clarify the role of cytochrome innitrate reductase we have performed spectrophotometric and stopped-flow kinetic studies of reduction and oxidation of the cytochrome hemes with analogues of physiological quinones, using menadione as an analogue of menaquinone and duro-quinone as an analogue of ubiquinone, and comparing the results with those obtained with dithionite. The spectropho-tometric studies indicate that reduction of the cytochrome hemes varies according to the analogue of quinoneused, and in no cases is it complete....

8p dell39 03-04-2013 54 3   Download

Several ribonucleases, including onconase anda-sarcin, are known to be toxic to tumor cells. On the other hand, although its structure is relatedto thatofa-sarcin,RNase T1 is noncytotoxic because of its inability to internalize into tumor cells. In this study, we internalized RNase T1 into human tumor cells via a novel gene transfer reagent, hem-agglutinating virus of Japan (HVJ) envelope vector, which resulted in cell death.

6p dell39 03-04-2013 37 5   Download

Sulfotransferases (SOTs) catalyse the transfer of a sulfate group from 3¢-phosphoadenosine 5¢-phosphosulfate (PAPS) to an appropriate hydroxy group of various substrates with the parallel formation of 3¢-phospho-adenosine 5¢-phosphate. In Arabidopsis thaliana, 18 SOT proteins (AtSOT) have been identified.

15p dell39 27-03-2013 25 2   Download