NON ligands

The linearity of the product of the Shell process is higher, 75-90% versus 60-70% for the non-ligand modified process. The reason for this is not entirely clear on steric grounds one might expect that the linear alkyl and acyl complexes are more stable leading to a higher linearity. Electronically the effects on rate and selectivity cannot be easily rationalised. 

The hydrogenation activity is an added advantage of this route, since most of the hydroformylation-products are converted to the alcohols anyway. Concurrent with the hydrogenation of aldehyde to alcohol, however, hydrogenation of alkene feedstock to alkane occurs, which may be as high as 15% under certain conditions (versus 2-3% for the non-ligand-modified... 

Table III. Spin Hamiltonian Parameters for Liganded and Non-Liganded Native and Modified Galactose Oxidase0...

Oxidation of this tryptophan in galactose oxidase also prevents alkylation of the histidine residue. Alkylation of the histidine residue in turn markedly affects the fluorescence quantum yield of this tryptophan (43) and nearly abolishes the absorbance of the copper atom. The copper atom itself is also essential to the reactivity of this histidine. Thus, we appear to have a consistent set of highly interdependent components. Not unexpectedly, the copper site cannot be fully understood without considering its interactions with non-ligand protein groups. 

The conclusions are (1) oxidative addition is efficient with Ni and Pd (2) the Pd insertion products are more stable than the Ni analogs, but in no case are the non-ligand-stabilized species isolable (3) decomposition of the insertion products first proceeds by CO elimination with formation of the alkyl- or aryl palladium chloride, which if unstable can decompose to a variety of products including PdCl2, Pd, alkyl or aryl chloride, and coupling products. 

Carbamate insecticides Herbicides ER agonist - after metabolism endocrine modulators, non-ligand binding... 

Gonzalez, M. M. and Carlberg, C. (2002) Cross-repression, a functional consequence of the physical interaction of non-liganded nuclear receptors and POU domain transcription factors. J. Biol. Chem. 277, 18501-18509. 

The dependence of the activity of calcineurin on the redox state of the metal center highlights its importance for catalysis and provides clues to its function in that process. Site-directed mutagenesis studies of PPl, calcineurin, and bacteriophage X protein phosphatase have also provided insights regarding the roles of non-ligand active site residues. Furthermore, the contributions afforded by studies of synthetic model compounds which mimic features of metallophosphatase active sites provide important clues to possible catalytic mechanisms. Indeed many of these models exhibit impressive rate enhancements for phosphate and phosphonate ester hydrolysis [54-62]. In this section we discuss current models regarding the mechanism of phosphate ester hydrolysis by calcineurin and other metallophosphatases in consideration of these studies. 

Table 17-2 Kinetic analyses of mutants of non-ligand active site residues of calcineurin, X protein phosphatase and protein phosphatase 1... 

Figure 17-13 Schematic of the active site of kidney bean purple acid phosphatase with phosphate bound. Non-ligand residues His 202, Asp 169, His 295, and His 296 are represented.

Intracellular receptors are a class of ligand-dependent transcription factors that include receptors for both steroid and non-steroid hormones. In the non-liganded state, these receptors reside in the cytoplasm and/or in the nucleus. Upon binding to the hormone, these receptors homo- or heterodimerize, then regulate, positively or negatively, gene expression by binding to specific sequences in the chromatin, termed HRE (hormone responsive element). 

D, E, an F) A) Non-liganded ApoIPBP, B) BmorPBP complexed with bombykol, C) Homology model of LdisPBPl threaded onto the BmorPBP solved structure with (-) disparlure docked. 

Y. Zhou, F. S. Riehle, Y. Yuan, H.-F. Schleiermacher, M. Niggemann, G. A. Urban, M. Kruger, Improved Efficiency of Hybrid Solar Cells Based on Non-Ligand-Exchanged CdSe Quantum Dots and Poly(3-Hexylthiophene). Applied Physics Letters 2010,96,013304. 

A number of circumstances led to the removal of putative ligands (i) non-protein macromolecule, for example, DNA or RNA (ii) commonly occurring non-ligands, for example, glycerol and tartaric acid, that were automatically identified and excluded on the basis of their PDB residue ID (GOL and TAR, respectively) and (iii) molecules... 

The third, and, we feel most reasonable explanation is the presence in the active site of a bound buffer species. At equilibrium, this proton transfer group would alternately protonate and deprotonate, as the enzyme correspondingly dehydrated and hydrated CO2 species, free of proton diffusion limitations. The most likely candidate for this internal buffer is the imidazole of the conserved non-ligand histidine in the active site of carbonic anhydrase (His -64 in HCAC), as proposed earlier(3,24,26,29). 

Obviously, in Rh-catalyzed hydroformylation extreme care has to be taken to avoid all loss of the precious metal compound from the process. This requires keeping the metal in its most stable active form in the process and avoiding any process conditions that would harm the catalyst s life-time. This is the reason why no industrial process is known that uses non-ligand-modified Rh-catalysis even though pure Rh-carbonyl is an active hydroformylation catalyst. The breakthrough in industrial Rh-catalyzed hydroformylation came with the discovery of triarylphosphine-... 

Ligand bond Non-ligand bond -.V0- Hydrogen bond and its length... 

Non-ligand residues involved in hydrophobic contact(s) Corresponding atoms involved in hydrophobic contact(s) Conserved residues involved in dCTP binding... 

---