Constrained region

It is possible to constrain peptides by introducing two codons for cysteine in both sites of the random region. Constraining a peptide in its active conformation is an advantage, but if it is constrained into an incorrect conformation, binding to the target molecule can be prevented. Several peptides have been isolated from cyclic libraries. The screening of pools... 

Rg. 17. Schematic diagram showing the craze-dominated DCG regions constrained on the sides and terminated in the front by shear fatigue fracture regions... 

The amphJ gene encodes modules 15-17. Modules 15 and 17 both contain DH-KR reductive loops. The structure of the polyketide suggests that neither of these DH domains is functional. However, DH15 contains the features of an active DH domain. It is possible that the interdomain linker regions constrain domain movements so that access to the substrate is not allowed. DH17 is clearly inactive since the active site histidine is replaced by an arginine residue. Module 16 contains a complete DH-ER-KR reductive loop. The main difference between the amphotericin and nystatin PKSs is that the reductive loops are different in modules 15 and 16. In the Nys J protein, module 15 contains a complete reductive loop, whereas modules 16 and 17 contain DH-KR reductive loops in which the DH domains must be nonfunctional although they may contain conserved active-site motifs. 

Very little has been reported about the use of spectroscopic methods for monitoring and control of other polymerization systems. Lenzi et al. [191] reported that the NIR spectra collected in a dispersive instrument with a transflectance probe may contain very useful information about the structure of core-shell polystyrene beads produced through simultaneous semibatch emulsion/suspension polymerizations. Lenzi et al. [192] developed a polymerization technique that combines recipes of typical emulsion and suspension polymerizations to produce core-shell polymer beads. More interesting, the appearance of the core-shell structure always led to qualitatively different NIR spectra that could not have been obtained with polymer suspensions, polymer emulsions, or mixtures of polymer suspensions and emulsions. As described by Lenzi et al. [191], different spectral peaks could be detected in the wavelength region constrained between 1700 and 1900nm when the core-shell structure developed. 

Start at the pinch. The pinch is the most constrained region of the problem. At the pinch, exists between all hot and cold... 

An approximate treatment of the phenomenon of capillary rise is easily made in terms of the Young-Laplace equation. If the liquid completely wets the wall of the capillary, the liquids surface is thereby constrained to lie parallel to the wall at the region of contact and the surface must be concave in shape. The... 

An important further consequence of curvature of the interaction region and a late barrier is tliat molecules that fail to dissociate can return to the gas-phase in vibrational states different from the initial, as has been observed experunentally in the H2/CU system [53, ]. To undergo vibrational (de-)excitation, the molecules must round the elbow part way, but fail to go over the barrier, eitlier because it is too high, or because the combination of vibrational and translational motions is such that the molecule moves across rather than over the barrier. Such vibrational excitation and de-excitation constrains the PES in that we require the elbow to have high curvature. Dissociation is not necessary, however, for as we have pointed out, vibrational excitation is observed in the scattering of NO from Ag(l 11) [55]. 

The free energy differences obtained from our constrained simulations refer to strictly specified states, defined by single points in the 14-dimensional dihedral space. Standard concepts of a molecular conformation include some region, or volume in that space, explored by thermal fluctuations around a transient equilibrium structure. To obtain the free energy differences between conformers of the unconstrained peptide, a correction for the thermodynamic state is needed. The volume of explored conformational space may be estimated from the covariance matrix of the coordinates of interest, = ((Ci [13, lOj. For each of the four selected conform-... 

In eontrast, if the eleetron is eonstrained to remain within a fixed area in the x,y plane (e.g., a reetangular or eireular region), then the situation is qualitatively different. Constraining the eleetron to any sueh speeified area gives rise to so-ealled boundary eonditions that impose additional requirements on the above A and B funetions. 

The detection of a specific gas (10) is accompHshed by comparing the signal of the detector that is constrained to the preselected spectral band pass with a reference detector having all conditions the same except that its preselected spectral band is not affected by the presence of the gas to be detected. Possible interference by other gases must be taken into account. It may be necessary to have multiple channels or spectral discrimination over an extended Spectral region to make identification highly probable. Except for covert surveillance most detection scenarios are highly controlled and identification is not too difficult. 

The primary photochemical act, subsequent to near-uv light (wavelengths <400 nm) absorption by Ti02 particles, is generation of electron—hole pairs where the separation (eq. 3) into conduction band electrons (e g ) and valence band holes (/lyB ) faciUtated by the electric field gradient in the space charge region. Chemically, the hole associated with valence band levels is constrained at... 

Effect of Temperature and pH. The temperature dependence of enzymes often follows the rule that a 10°C increase in temperature doubles the activity. However, this is only tme as long as the enzyme is not deactivated by the thermal denaturation characteristic for enzymes and other proteins. The three-dimensional stmcture of an enzyme molecule, which is vital for the activity of the molecule, is governed by many forces and interactions such as hydrogen bonding, hydrophobic interactions, and van der Waals forces. At low temperatures the molecule is constrained by these forces as the temperature increases, the thermal motion of the various regions of the enzyme increases until finally the molecule is no longer able to maintain its stmcture or its activity. Most enzymes have temperature optima between 40 and 60°C. However, thermostable enzymes exist with optima near 100°C. 

The foregoing approaches used an umbrella potential to restrain q. The pmf W(q) can also be obtained from simulations where q is constrained to a series of values spanning the region of interest [48,49]. However, the introduction of rigid constraints complicates the theory considerably. Space limitations allow only a brief discussion here for details, see Refs. 8 and 50-52. 

In a synchrotron, electrons are accelerated to near relativistic velocities and constrained magnetically into circular paths. When a charged particle is accelerated, it emits radiation, and when the near-relativistic electrons are forced into curved paths they emit photons over a continuous spectrum. The general shape of the spectrum is shown in Fig. 2.4. For a synchrotron with an energy of several gigaelectronvolts and a radius of some tens of meters, the energy of the emitted photons near the maximum is of the order of 1 keV (i.e., ideal for XPS). As can be seen from the universal curve, plenty of usable intensity exists down into the UV region. With suitable mono-... 

Sometimes LNG is the only option in regions and countries where political issues constrain pipeline development. 

We recall from our earlier discussion of chaos in one-dimensional continuous systems (see section 4.1) that period-doubling is not the only mechanism by which chaos can be generated. Another frequently occurring route to chaos is intermittency. But while intermittency in low dimensional dynamical systems appears to be constrained to purely temporal behavior [pomeau80], CMLs exhibit a spatio-temporal intermittency in which laminar eddies are intermixed with turbulent regions in a complex pattern in space-time. 

If the fit is poor and it is suspected that the full concentration range of data has not been tested, the top and/or bottom of the fit may be constrained if no data are available in these regions. If control data from other sources are available, this may be used to constrain maxima and/or minima. 

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