Laue diffraction

PL Howell, SC Almo, MR Parsons, I Hajdu, GA Petsko. Stiaicture determination of turkey egg-white lysozyme using Laue diffraction data. Acta Crystallogr B, 48 200-207, 1992. 

Mosaic spread derived from the asterism of the diffracted X-ray beams in the Laue diffraction, mentioned above [2]... 

The mathematics necessary to understand the diffraction of X rays by a crystal will not be discussed in any detail here. Chapter 4 of reference 10 contains an excellent discussion. The arrangement of unit cells in a crystal in a periodic manner leads to the Laue diffraction conditions shown in equations 3.3 where vectors a, b, and c as well as lattice indices h, k, and l have been defined in Figure 3.5 and S is a vector quantity equal to the difference between the resultant vector s after diffraction and the incident X-ray beam wave vector So so that S = s - So-... 

Fig. 8. A full white beam Laue diffraction pattern recorded from a crystal of glycogen phosphorylase b, and (P4(3)2(l)2 a = b = 128.8 A, c= 116.2 A) using a 0.2 mm diameter collimator the exposure time was 0.5 s...

Fig. 9a and b. Difference Fourier maps calculated from Laue diffraction data showing maltoheptose bound in phosphorylase b. The Laue map shown in a is calculated with a subset of 9029 unique data at 2.5 A resolution. A positive contour at half maximal peak height is shown, b is an enlargement of a and shows 4 of the 7 sugar units, the 3 central units have the highest occupancies. Side chain movements produce the two extra lobes of density. (Figures courtesy of J. Hajdu)... 

The SR spectnun of an intense energy continuum of radiation makes possible rapid data collection in the sub-second regime by the Laue diffraction method. This rate of data collection is sufficient to investigate some of the crystal kinetics and catalytic intermediate reaction states that can be produced. 

Fig. 14. A Laue diffraction photograph from cytochrome c using quasi-white X-ray radiation (X 0.1-0.19 nm)...

The five years since last considering specifically recent developments in X-ray and neutron diffraction methods for zeolites [1] have witnessed substantial progress. Some techniques, such as high resolution powder X-ray diffraction using synchrotron X-rays, have blossomed from earliest demonstrations of feasibility to widespread and productive application. Others, such as neutron powder diffraction, have shown steady progress. For still others, notably microcrystal diffraction, a variety of circumstances have contributed to extended gestation periods. Additionally, opportunities scarcely considered earlier (such as single crystal Laue diffraction, and certain developments in computer simulations that complement diffraction work) now command broad attention and warrant the commitment of substantial further investment. 

Szebenyi, D. M. E., Bilderback, D. H., LeGrand, A., et al. 1992. Quantitative analysis of Laue diffraction pattern recorded with a 120 ps exposure from an X-ray undulator. J. Appl. Cryst. 25 414-23. 

The advantages of using polychromatic radiation from a reactor source, coupled with Laue diffraction methods, have been investigated by McIntyre et al. for high-pressure studies [194]. Using a 0.5-mm crystal in a moissanite anvil pressure cell... 

Wulff M, Schotte F, Naylor G, Bourgeois D, Moffat K, Mourou G (1997) Time-resolved stmctures of macromolecules at the ESRF single-pulse Laue diffraction, stroboscopic data collection and femtosecond flash photolysis. Nucl Instr Meth Phys Res A 398 69-84... 

Fig. 1. Spectra from the U17 undulator. The red curve is the 6.0 mm gap spectrum used for Laue diffraction from proteins and the black curve, the 10.4 mm gap spectrum used for liquid experiments.

We have used x-ray diffraction in our laboratory to probe transient structures of laser-excited liquids, small-molecule crystals and protein crystals. The diffraction patterns are recorded on a CCD detector that makes efficient use of most of the diffracted x-rays. Several experimental protocols have been developed Laue diffraction from proteins [6-8], small-molecule diffraction [9,10] and diffraction from liquids [2,11,12]. In proteins, the... 

Now I return to X-ray diffraction to describe probably the oldest type of diffraction experiment, but one whose stock has soared with the advent of synchrotron radiation and powerful computer techniques for the analysis of complex diffraction data. The method, Laue diffraction, is already realizing its promise as a means to determine the structures of short-lived reaction intermediates. This method is sometimes called time-resolved crystallography, implying an attempt to take snapshots of a chemical reaction or physical change in progress. 

Geometric construction for Laue diffraction in reciprocal space. 

You can see from Fig. 9.8 that a Laue diffraction pattern is much more complex than a diffraction pattern from monochromatic X rays. But modern software can index Laue patterns and thus allow accurate measurement of many diffraction intensities from a single brief pulse of X rays through a still crystal. If the crystal has high symmetry and is oriented properly, a full data set can in theory be collected in a single brief X-ray exposure. In practice, this approach usually does not provide sufficiently accurate intensities because the data lack the redundancy necessary for high accuracy. Multiple exposures at multiple orientations are the rule. 

For an example of Laue diffraction applied to time-resolved crystallography, see V. Srajer, T. Teng, T. Ursby, C. Pradervand, Z. Ren, S. Adachi, W. Schildkamp, D. Bourgeois, M. Wulff, and K. Moffat, Photolysis of the carbon monoxide complex of myoglobin Nanosecond time-resolved crystallography, Science 274, 1726-1729, 1996. 

Hajdu, J., and Johnson, L. N. Progress with Laue diffraction studies on proteins and virus crystals. Biochemistry 29, 1669-1678 (1990). 

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