Determination of Absolute from Relative X-Ray Intensity Data

Wilson, A. J. C.

doi:10.1038/150152a0

Cited by 760 publications

(475 citation statements)

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“…The relevant data reduction statistics are presented in Table 3. Wilson plots (Wilson, 1942) revealed that the data for inhibitors l a and Ib were usable to 2.1 A, while the IC complex was usable to 1.6 A. Model building was started using the refined native structure (Eriksson et al, 1988) as taken from the Protein Data Bank (Bernstein et al, 1977).…”

Section: Methodsmentioning

confidence: 99%

Positions of His‐64 and a bound water in human carbonic anhydrase II upon binding three structurally related inhibitors

et al. 1994

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The 3-dimensional structure of human carbonic anhydrase I1 (HCAII; EC 4.2.1.1) complexed with 3 structurally related inhibitors, l a , l b , and I C , has been determined by X-ray crystallographic methods. The 3 inhibitors ( l a = C8H,2N204S3) vary only in the length of the substituent on the 4-amino group: l a , proton; Ib, methyl; and IC, ethyl. The binding constants (Ki's) for la, Ib, and I C to HCAII are 1.52, 1.88, and 0.37 nM, respectively. These structures were solved to learn if any structural cause could be found for the difference in binding. In the complex with inhibitors l a and l b , electron density can be observed for His-64 and a bound water molecule in the native positions. When inhibitor IC is bound, the side chain attached to the 4-amino group is positioned so that His-64 can only occupy the alternate position and the bound water is absent. While a variety of factors contribute to the observed binding constants, the major reason IC binds tighter to HCAII than does l a or l b appears to be entropy: the increase in entropy when the bound water molecule is released contributes to the increase in binding and overcomes the small penalty for putting the His-64 side chain in a higher energy state.

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Section: Methodsmentioning

confidence: 99%

Positions of His‐64 and a bound water in human carbonic anhydrase II upon binding three structurally related inhibitors

et al. 1994

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“…Comme pour la forme I, le module mol6culaire qui a 6t6 utilis6 dans les calculs est celui de Bak et al (1955); des valeurs approch6es pour le facteur moyen d'agitation thermique et les facteurs d'6chelle ont 6t6 obtenues par la m6thode statistique de Wilson (1942). La valeur minimum de R correspond b. x= 0,08 et ~0 = 45,8 °.…”

Section: Rdsolution De La Structureunclassified

Etude par diffraction X des structures cristallines du furanne à la pression atmosphérique

Fourme¹

1972

Acta Crystallogr Sect B

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“…10. The procedure employed here is identical to the widely employed Wilson's zone-averaging method (Wilson, 1942). The solid-line curve in Fig.…”

Section: Determination Of Space Groupmentioning

confidence: 99%

Crystal Structures of Cubic and Trigonal Yttrium Hypocarbides; A Dimorphically Interphased Single-Crystal Study

Atoji

Kikuchi

1969

The Journal of Chemical Physics

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X-ray structure determinations on the cubic YCx (x ≈ 0.3 − 0.7, stable above about 900°C) and the trigonal Y2C (stable below 900°C) have been carried out using a quenched “single crystal” in which a transient state in the midst of the cubic-to-trigonal transition has been arrested. Our “single crystal” is composed of one cubic and four trigonal single crystals, the trigonal c axis being parallel to one of four cubic body-diagonal axes. The cubic structure is of NaCl type with random holes in the carbon-atom sites and with a = 5.115 ± (2) Å for YC0.44. The ordering of the carbon atoms creates the anti-CdCl2-type trigonal Y2C with the yttrium positional parameter z = 0.2585 ± (3) in the hexagonal-based unit cell, a = 3.617 ± (2) and c = 17.96 ± (1) Å, containing three Y2C formula units. Mo Kα x-ray was employed, and consequently the dispersion corrections on the atomic scattering factor of Y amount to 10%–20% of the nondispersion value and are considerably larger than the carbon-scattering factor. The structure analyses with and without the dispersion corrections demonstrate that even these unusually large corrections do not modulate the Y and C positional parameters significantly. The x-ray single-crystal results were further substantiated by the neutron-powder analysis. The present work confirmed unambiguously not only the reported x-ray powder results as well as the neutron-powder data of the isostructural Ho2C, but also yielded the structural parameters with a much higher accuracy, hence providing detailed insights into the chemical-bonding correlation in the order–disorder transition.

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Determination of Absolute from Relative X-Ray Intensity Data

Cited by 760 publications

References 0 publications

Positions of His‐64 and a bound water in human carbonic anhydrase II upon binding three structurally related inhibitors

Positions of His‐64 and a bound water in human carbonic anhydrase II upon binding three structurally related inhibitors

Etude par diffraction X des structures cristallines du furanne à la pression atmosphérique

Crystal Structures of Cubic and Trigonal Yttrium Hypocarbides; A Dimorphically Interphased Single-Crystal Study

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