Y-encoding

Taking the MREV-8 as a basic C element (duration = xr/5), one can generate a y -encoded [194] version of MREV-8 by concatenating the five C elements with an rf phase set equal to k / 2n/5, where k = 0-4 [107]. The averaged Hamiltonian calculated to the lowest order for this so-called T-MREV method has the following form ... 

Sudden recoupling method Adiabatic recoupling method ZQorDQ method y-encoding References... 

Clearly, y encodes more relevant information (probably size) than does log Kow, which does contain a size component, but also contains hydrogen bonding and polarity/polarizability components (Dearden and Bentley, 2002). Log Kow would, however, be expected to be a better descriptor for polar chemicals. In connection with this, Gerstl and Helling (1987) commented that the ability of molecular connectivities to predict log Koc was rather limited for diverse data sets. Baker et al. (2001) included two cluster connectivity terms to improve the correlation of soil sorption of a small hydrophobic data set, yielding R2 = 0.806 and 5 = 0.302. 

Indmdual E does express X mRNA but is unable to synthesize protein Y encoded by this mRNA (perhaps a regulatory mutation). (Alternatively, E could possibly make a defective protein Y that does not fold properly or is degraded rapidly and is not recognized by the antibody in the Western blot.)... 

An improved variant of the popular double cross-polarisation (DCP) experiment for heteronuclear dipolar re-coupling in solid state NMR spectroscopy under MAS was introduced by Bjerring and Nielsen. By simple phase and amplitude modulation of the RF irradiation at the Hartman-Hahn sideband conditions, the new pulse sequence, dubbed iDCP, was shown to enable broadband excitation with the high efficiency of y-encoded coherence transfer. The efficiency and robustness of iDCP towards isotropic chemical shift variations and chemical shift anisotropies in the case of uniformly C, N-labelled proteins has been demonstrated numerically and experimentally by N to C coherence transfer for N-labelled N-Ac-L-valyl-L-leucine and C, N-labelled-L-threonine. 

Table 4-3 lists various recoupling techniques, which have been applied to liquid crystals. The methods are eompared in terms of heteronuclear dipolar scaling factor, y-encoding property, sensitivity to frequency offsets and chemical shift anisotropy of S (rare) and I (abundant) spins, tolerance to rf inhomogeneity, accomplishment of active homonuclear proton decoupling, length of rf cycle time (which limits the maximum spectral width in dipolar dimension), and requirement of rotor... 

Method Scaling factor y- encoding S offset S CSA I offset I CSA RF inhom. I homo--dec. Short cycle Asynch time -ronous Ref. 

Figure Bl.14.2. Gradient-recalled echo pulse sequence. The echo is generated by deliberately dephasing and refocusing transverse magnetization with the readout gradient. A slice is selected in the z-direction and v- and y-dimension are frequency and phase encoded, respectively.

AMP-activated protein kinases are heterotrimeric complexes comprised of catalytic a subunits and regulatory (3 and y subunits (Table 1). Each subunit is encoded by at least two genes, some of which can also be subject to alternate splicing, leading to a diverse array of possible heterotrimeric combinations. 

In mammalia, seven different members encoded by distinct genes have been identified, all of which are activated by a distinct set of cytokines. Diversity in signaling is provided by variants of STAT proteins derived from either alternative splicing of RNA transcripts or proteolytic processing (e.g., STATs 1,3,4, and 5) and the ability of certain STATs to form both homodimers and heterodimers with each other. In response to inteiferon-y monomeric STAT1 dimerizes, while upon interferon-a stimulation a heterotrimeric complex consisting of STAT 1 and STAT2 with associated... 

Izumi, R., Yamada, T., Yoshikai, S., Sasaki, H., Hattori, M., Sakaki, Y. (1992). Positive and negative regulatory elements for the expression of the Alzheimer s disease amyloid precursor-encoding gene in mouse. Gene 112, 189-195. 

Not only eukaryotic cells but also bacteria have successfully been targeted by PNA anhsense strategies. Thus it has been shown that PNA complementary to ribosomal RNA or mRNA encoding an essential fatty acid biosynthesis protein, effectively kills E. coli. Furthermore, it has been shown that PNA directed to the start codon of the y -lactamase gene re-sensitized otherwise resistant E. coli to the antibiohc ampiciUin [64—66]. Conjugating a simple transporter peptide to the PNA increased the potency significantly, and an even more potent antibacterial PNA... 

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