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Müller, Gerhard; Löffelholz, Josef

doi:10.1007/978-3-663-00090-7_21

Cited by 5 publications

(5 citation statements)

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“…Thus diazepam, which was located in the crystal structure in the IIIA site, inhibited the reaction by up to 30%. Since only a single association constant was measured this may be the only inhibitor that is specific for a single site ( K d = 2 μM), although it is possible that a second association constant was missed. This is possible also for warfarin: up to 3 molar equiv gave 54% of inhibition, but at higher molar excesses further inhibition could be observed.…”

Section: Resultsmentioning

confidence: 99%

Characterization of Proton-Transfer Catalysis by Serum Albumins

et al. 2000

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Two independent investigations of catalysis by BSA and other serum albumins are combined to provide detailed insight into the mechanism of a classical proton-transfer reaction taking place on the surface of a protein. The Kemp elimination involves the general base-catalyzed removal of a proton from carbon and is known to be highly sensitive to medium effects. The serum albumins bind and catalyze the eliminative fragmentation of 5-nitrobenzisoxazole with remarkable efficiency and "accidental specificity." A binding site and a likely catalytic lysine are identified, and factors contributing to the efficiency of catalysis analyzed. A key factor appears to be a differentiated microenvironment, which allows delocalized negative charge to develop in a stabilizing hydrophobic pocket next to a polar region where the developing ammonium cation is not disfavored. Catalytic efficiency is discussed in terms of effective molarities for the reaction catalyzed by serum albumins and by catalytic antibodies and compared with a selection of published EMs for enzyme-catalyzed reactions.

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Section: Resultsmentioning

confidence: 99%

Characterization of Proton-Transfer Catalysis by Serum Albumins

et al. 2000

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“…[8] [9] The NaϪN α ϪN β angles were found to vary between 127.6(1)°(NaϪN6ϪN5) and 150.0(2)°(NaϪN3ϪN2). The corresponding values at the aluminium centre range from 129.3(1)°(AlϪN1ϪN2) to 132.8(1)°(AlϪN4ϪN5), which are similar to the angles found in other covalent metal azides and are thus indicative of sp 2 hybridization at the N α atoms.…”

Section: Crystal Structuresmentioning

confidence: 99%

Tetraazido Complexes of Aluminium, Gallium, and Indium

Sussek¹,

Stowasser²,

Pritzkow³

et al. 2000

Eur. J. Inorg. Chem.

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“…N+ angles of 90" [30]. The N;-ion of NH,N, is tetra-coordinated forming two H-bonds between each of its terminal N-atoms and NHl-cations [22] [23]. Despite the fragmentary literature data available, it is clear that the large number and the arrangement of the binding sites made available by macropolycyclic anion receptors allows to attain much higher coordination number and much better defined geometries.…”

Section: ") Dmentioning

confidence: 99%

“…= F-, C1-, Br-, N ; ) . The three substrate anions F-, C1-and Br-are spherical species of increasing size ( Table 3); N; may be considered as grossly cylindrical with a length of about 5.5 8, (end-to-end distance: 2.33 A + 2 x ionic radius of a Nsite: 2 x 1.6 A [23]) and a diameter of 2 x 1.6 = 3.2 A. The receptor molecule BT-6H' is of ellipsoidal shape, with cavity dimensions of about 4.5 A and 2.5-3.0 for the long and short axes, respectively, in a conformationally relaxed state like that of the N;cryptate (Table 2) ; this cavity may be approximated by a cylinder of diameter ( z 5.0 A) defined by the circles passing through the three protonated N-sites at each pole of the molecule and of length ( z 5.5 A) equal to the distance between these circles.…”

Section: ") Dmentioning

confidence: 99%

Molecular Recognition in Anion Coordination Chemistry. Structure, Binding Constants and Receptor‐Substrate Complementarity of a Series of Anion Cryptates of a Macrobicyclic Receptor Molecule

Dietrich¹,

Guilhem

Lehn³

et al. 1984

Helvetica Chimica Acta

225

115

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SummaryThe crystal structures of four anion cryptates [X-c BT-6H'I formed by the protonated macrobicyclic receptor BT-6H+ with F-, C1-, Br-and N; have been determined. They provide a homogeneous series of anion coordination patterns with the same ligand. The small F--ion is tetra-coordinated, while C1-and Br-are bound in an octahedron of H-bonds. The non-complementarity between these spherical anions and the ellipsoidal cavity of BT-6H+ is reflected in ligand distortions. Structural complementarity is achieved for the linear triatomic substrate N;, which is bound by two pyramidal arrays of three H-bonds, each interacting with a terminal N-atom of N;. The formation constants of the complexes formed by BT-6H' with a variety of anions (halides, N;, NO;, carboxylates, SO:-, HPO:-, AMP2-, ADP3-, ATP4-, P,O:-) have been determined. Very strong complexations are found, as well as marked electrostatic and structural effects on stability and selectivity; in particular the binding of F-, C1-, Br-and N; may be analyzed in terms of the crystal structure data. The cryptand BT-6H+ is a molecular receptor containing an ellipsoidal recognition site for linear triatomic substrates of size compatible with the size of the molecular cavity. Further developments of various aspects of anion coordination chemistry are considered.

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U

Cited by 5 publications

References 0 publications

Characterization of Proton-Transfer Catalysis by Serum Albumins

Characterization of Proton-Transfer Catalysis by Serum Albumins

Tetraazido Complexes of Aluminium, Gallium, and Indium

Molecular Recognition in Anion Coordination Chemistry. Structure, Binding Constants and Receptor‐Substrate Complementarity of a Series of Anion Cryptates of a Macrobicyclic Receptor Molecule

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