297 research outputs found
Sweetening of Glutamine Metabolism in Cancer Cells by Rho GTPases Through Convergence of Multiple Oncogenic Signaling Pathways
Comment on: Lukey MJ, Greene KS, Erickson JW, et al. The oncogenic transcription factor c-Jun regulates glutaminase expression and sensitizes cells to glutaminase-targeted therapy. Nat Commun 2016;7:11321
Kynurenine Aminotransferase III and Glutamine Transaminase L Are Identical Enzymes That Have Cysteine S-Conjugate Beta-Lyase Activity and Can Transaminate L-Selenomethionine
Three of the four kynurenine aminotransferases (KAT I, II, and IV) that synthesize kynurenic acid, a neuromodulator, are identical to glutamine transaminase K (GTK), α-aminoadipate aminotransferase, and mitochondrial aspartate aminotransferase, respectively. GTK/KAT I and aspartate aminotransferase/KAT IV possess cysteine S-conjugate β-lyase activity. The gene for the former enzyme, GTK/KAT I, is listed in mammalian genome data banks as CCBL1 (cysteine conjugate beta-lyase 1). Also listed, despite the fact that no β-lyase activity has been assigned to the encoded protein in the genome data bank, is a CCBL2 (synonym KAT III). We show that human KAT III/CCBL2 possesses cysteine S-conjugate β-lyase activity, as does mouse KAT II. Thus, depending on the nature of the substrate, all four KATs possess cysteine S-conjugate β-lyase activity. These present studies show that KAT III and glutamine transaminase L are identical enzymes. This report also shows that KAT I, II, and III differ in their ability to transaminate methyl-L-selenocysteine (MSC) and L-selenomethionine (SM) to β-methylselenopyruvate (MSP) and α-ketomethylselenobutyrate, respectively. Previous studies have identified these seleno-α-keto acids as potent histone deacetylase inhibitors. Methylselenol (CH3SeH), also purported to have chemopreventive properties, is the γ-elimination product of SM and the β-elimination product of MSC catalyzed by cystathionine γ-lyase (γ-cystathionase). KAT I, II, and III, in part, can catalyze β-elimination reactions with MSC generating CH3SeH. Thus, the anticancer efficacy of MSC and SM will depend, in part, on the endogenous expression of various KAT enzymes and cystathionine γ-lyase present in target tissue coupled with the ability of cells to synthesize in situ either CH3SeH and/or seleno-keto acid metabolites
Implementation of a Deutsch-like quantum algorithm utilizing entanglement at the two-qubit level, on an NMR quantum information processor
We describe the experimental implementation of a recently proposed quantum
algorithm involving quantum entanglement at the level of two qubits using NMR.
The algorithm solves a generalisation of the Deutsch problem and distinguishes
between even and odd functions using fewer function calls than is possible
classically. The manipulation of entangled states of the two qubits is
essential here, unlike the Deutsch-Jozsa algorithm and the Grover's search
algorithm for two bits.Comment: 4 pages, two eps figure
Hadamard NMR spectroscopy for two-dimensional quantum information processing and parallel search algorithms
Hadamard spectroscopy has earlier been used to speed-up multi-dimensional NMR
experiments. In this work we speed-up the two-dimensional quantum computing
scheme, by using Hadamard spectroscopy in the indirect dimension, resulting in
a scheme which is faster and requires the Fourier transformation only in the
direct dimension. Two and three qubit quantum gates are implemented with an
extra observer qubit. We also use one-dimensional Hadamard spectroscopy for
binary information storage by spatial encoding and implementation of a parallel
search algorithm.Comment: 28 pages, 10 figures. Journal of Magnetic Resonance (In Press
A NEW POLICY FOR THE SERVICE REQUEST ASSIGNMENT PROBLEM WITH MULTIPLE SEVERITY LEVEL, DUE DATE AND SLA PENALTY SERVICE REQUESTS
We study the problem of assigning multiple severity level service requests to agents in an agent pool. Each severity level is associated with a due date and a penalty, which is incurred if the service request is not resolved by the due date. Motivated by Van Meighem (2003), who shows the asymptotic optimality of the Generalized Longest Queue policy for the problem of minimizing the due date dependent expected delay costs when there is a single agent, we develop a class of Index-based policies that is a generalization of the Priority First-Come-First-Serve, Weighted Shortest Expected Processing Time and Generalized Longest Queue policy. In our simulation study of an assignment system of a large technology firm, the Index-based policy shows an improvement of 0-20 % over the Priority First-Come-First-Serve policy depending upon the load conditions.
Experimental Implementation of the Deutsch-Jozsa Algorithm for Three-Qubit Functions using Pure Coherent Molecular Superpositions
The Deutsch-Jozsa algorithm is experimentally demonstrated for three-qubit
functions using pure coherent superpositions of Li rovibrational
eigenstates. The function's character, either constant or balanced, is
evaluated by first imprinting the function, using a phase-shaped femtosecond
pulse, on a coherent superposition of the molecular states, and then projecting
the superposition onto an ionic final state, using a second femtosecond pulse
at a specific time delay
Experimental Implementation of Hogg's Algorithm on a Three-Quantum-bit NMR Quantum Computer
Using nuclear magnetic resonance (NMR) techniques with three-qubit sample, we
have experimentally implemented the highly structured algorithm for the 1-SAT
problem proposed by Hogg. A simplified temporal averaging procedure was
employed to the three-qubit spin pseudo-pure state. The algorithm was completed
with only a single evaluation of structure of the problem and the solutions
were found with probability 100%, which outperform both unstructured quantum
and the best classical search algorithm.Comment: Revtex, 14 pages and 1 table, 4 EPS figure
Implementing universal multi-qubit quantum logic gates in three and four-spin systems at room temperature
In this paper, we present the experimental realization of multi-qubit gates
in macroscopic ensemble of three-qubit and four-qubit
molecules. Instead of depending heavily on the two-bit universal gate, which
served as the basic quantum operation in quantum computing, we use pulses of
well-defined frequency and length that simultaneously apply to all qubits in a
quantum register. It appears that this method is experimentally convenient when
this procedure is extended to more qubits on some quantum computation, and it
can also be used in other physical systems.Comment: 5 Pages, 2 Figure
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