Relations between integrated intensities in crystal diffraction methods for X-rays and neutrons

Buras, B.; Gerward, L.

doi:10.1107/s0567739475000782

Cited by 42 publications

(22 citation statements)

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“…In particular, the argument above can be repeated for time-of-flight neutron powder diffraction at fixed angle. The intensities in this case are simply related to those obtained in fixed-wavelength powder diffraction (Buras & Gerward, 1975). It can be shown that the scale factors obtained from Rietveld analysis of timeof-flight data [with multiphase versions of programs such as that described by Von Dreele, Jorgensen & *We note that a rather similar relationship has been given by Werner et al (1979), but it lacks the unit-cell volume V r an omission which we cannot understand.…”

Section: Sp W Mp/( Zpm Pvp)mentioning

confidence: 91%

Quantitative phase analysis from neutron powder diffraction data using the Rietveld method

Hill¹,

Howard²

1987

J Appl Crystallogr

1,177

606

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The weight of a phase in a mixture is proportional to the product of the scale factor, as derived in a multicomponent Rietveld analysis of the powder diffraction pattern, with the mass and volume of the unit cell. If all phases are identified and crystalline, the weight fraction W of phase p is given by Wp = Sp( Z M IO p/~ S,( Z M IO,, iwhere S, Z, M and V are, respectively, the Rietveld scale factor, the number of formula units per unit cell, the mass of the formula unit and the unit-cell volume. This is the basis of a method providing accurate phase analyses without the need for standards or for laborious experimental calibration procedures. The method is demonstrated by measurements on binary mixtures of rutile, corundum, silicon and quartz.

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Section: Sp W Mp/( Zpm Pvp)mentioning

confidence: 91%

Quantitative phase analysis from neutron powder diffraction data using the Rietveld method

Hill¹,

Howard²

1987

J Appl Crystallogr

1,177

606

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“…The Laue method (Friedrich, Knipping & yon Laue, 1912) gained new popularity in the 1970's (Tuomi, Naukkarinen & Rabe, 1974;Buras & Gerward, 1975;Steinberger, Bordas & Kalman, 1977) when synchrotron radiation became widely available for structural studies (Rosembaum, Holmes & Witz, 1971). This, along with developments in computational techniques to process Laue diffraction data (Wood, Thompson & Matthewman, 1983;Machin, 1985Machin, , 1987Campbell, Habash, Moffat & Helliwell, 1986;Clifton et al, 1985;Campbell et al, 1987;Rabinovich & Lourie, 1987;Cruickshank, Helliwell & Moffat, 1987HelliweU et al, 1989;), led to an expansion in the use of the Laue technique.…”

Section: Introductionmentioning

confidence: 99%

Structure determination of turkey egg-white lysozyme using Laue diffraction data

Howell

Almo²,

Parsons³

et al. 1992

Acta Crystallogr Sect B

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The three-dimensional structure of turkey egg-white lysozyme (TEWL) has been solved and refined at 2.5 A~ resolution using X-ray data collected by the Laue method. This is the first protein structure determination undertaken using Laue diffraction data. A re-examination of the existing structure of TEWL was necessary when attempts to refine an atomic model based on the C,~ positions in the Protein Data Bank (entry 1LZ2) failed. The correct orientation and position of the turkey lysozyme molecules within the crystallographic unit cell were determined by molecular replacement using a refined model of the homologous hen egg-white lysozyme crystal structure. After modification of the model to reflect the differences in amino-acid sequence between the chicken and turkey enzymes, the structure was subjected to crystallographic refinement using the simulated-annealing refinement technique and conventional least-squares refinement. This yielded a final residual of R = 20.7%. This crystal form is of potential interest for time-resolved crystallographic studies since the amino-acid residues involved in

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“…Unfortunately, these crystals have a brief lifetime when exposed to x-radiation. We therefore investigated the potential of the fast and efficient Laue data collection method (34)(35)(36) to obtain data of adequate quality to proceed with the crystal structure determination.…”

Section: Resultsmentioning

confidence: 99%

Structure of glycosomal glyceraldehyde-3-phosphate dehydrogenase from Trypanosoma brucei determined from Laue data.

Vellieux¹,

Hajdu

Verlinde

et al. 1993

Proc. Natl. Acad. Sci. U.S.A.

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The three-dimensional structure of glycosomal glyceraldehyde-3-phosphate dehydrogenase [D-glyceraldehyde-3-phosphate:NAD+ oxidoreductase (phosphorylating), EC 1.12.1.12] from the sleeping-sickness parasite Trypanosoma brucei was solved by molecular replacement at 3.2-A resolution with an x-ray data set collected by the Laue method. For data collection, three crystals were exposed to the polychromatic synchrotron x-ray beam for a total of 20.5 sec. The structure was solved by using the BaciUus stearothermophilus enzyme model [Skariyfiski, T., Moody, P. C. E. & Wonacott, A. J. (1987) J. Mol. Biol. 193, 171-187] with a partial data set which was 37% complete. The crystals contain six subunits per asymmetric unit, which allowed us to overcome the absence of >60% of the reflections by 6-fold density averaging. After molecular dynamics refinement, the current molecular model has an R factor of 17.6%. Comparing the structure of the trypanosome enzyme with that of the homologous human muscle enzyme, which was determined at 2.4-A resolution, reveals important structural differences in the NAD binding region. These are of great interest for the design of specific inhibitors of the parasite enzyme.

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Relations between integrated intensities in crystal diffraction methods for X-rays and neutrons

Cited by 42 publications

References 1 publication

Quantitative phase analysis from neutron powder diffraction data using the Rietveld method

Quantitative phase analysis from neutron powder diffraction data using the Rietveld method

Structure determination of turkey egg-white lysozyme using Laue diffraction data

Structure of glycosomal glyceraldehyde-3-phosphate dehydrogenase from Trypanosoma brucei determined from Laue data.

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