Crystallization macromolecules

Characterization of ligand-induced conformational changes in atomic detail has primarily been studied through comparison of high-resolution X-ray structures for macromolecules crystallized in both free and ligand-bound states. The possibility of monitoring such... 

Two weeks are enough for droplets of about 200 nl to 3 jl1 to equilibrate imder any conditions (Mikol et al., 1990). During this period, droplets should be inspected daily to foUow up the appearance of crystals. Crystals may still form after 2 weeks, but this is less likely in the case of oligonucleotides. Crystals can then be cryoprotected and frozen or capillary-mounted to be tested. Fluidigm markets crystallization chips dedicated to crystal growth optimization which can sustain and are transparent to X-rays in order to discriminate between salt and macromolecule crystals. Extracting the crystal from the chip is performed only for crystals deserving data collection. 

GiUiland, G. L., Tung, M. and Ladner, J. E. (2002). The Biological Macromolecule Crystallization Database procedures and strategies. Acta Crystallogr. D 58,916-920. 

The process of crystallization is still largely a process of trial and error, but in an attempt to formulate general rules, the cumulative experiences of X-ray crystallographers are being compiled into online databases such as the Marseille Protein Crystallization Database (14) and the Biological Macromolecule Crystallization Database (15). These and similar databases will provide useful starting points in crystallization trials and may greatly accelerate the process. 

Gilliland GL, Tung M, Blakeslee DM, Ladner JE. Biological macromolecule crystallization database, version-3.0 - New features, data and the NASA archive for protein crystal-growth data. Acta Cryst. D-Biol. Cryst. 1994 50 408-413. 

G. L.Gilliland, M. Tung, D. M. Blakeslee, and J. Ladner, Biological Macromolecule Crystallization Database (BMCD), available online at http /A[Pg.496]

Gilliland, G. L. A biological macromolecule crystallization database a basis for a crystallization strategy. Crystal Growth 90, 51-59 (1988). 

Macromolecule Crystals by STM and AFM STM and AFM Studies under Fluids Measurement of Attractive and Repulsive Forces by Atomic Force Microscope Diverse Applications of STM and AFM... 

Most macromolecules crystallize with about 50% or more solvent of crystallization. If an approximate value for the molecular weight is known, then the number of subunits per cubic Amay be found. Matthews (40) introduced ause-... 

A variety of studies on small organic, inorganic and macromolecule crystals has been done. In order to compare these it is useful to define a scattering strength for a given crystal which takes account of its volume and composition. Table 10.7 compares various studies in terms of the scattering strength of the sample that was examined in each case. 

Once crystals have been obtained, they must be isolated and prepared for X-ray crystal diffraction studies. This too is problematic, since biological macromolecule crystals are not the dense packed structures familiar to chemists used to working with small molecules. Rather,... 

For a completely accurate crystal structure determination. X-ray scattering must be observed and recorded by reflection from the vast majority of hfcHattice planes associated with a given biological macromolecule crystal. That is to say that an accurate structural determination is only possible if the vast majority of reciprocal lattice points can be sampled. In order to achieve this, the classical approach has been to use a device like a four-circle diffractometer (Figure 6.15) in which biological macromolecule crystals are first mounted in a goniometer head located at the centre of the diffractometer and then irradiated with an intense beam of X-rays, after which X-ray reflections may be observed sequentially, one at a time, in... 

The basic, macroscopic theories of matter are equilibrium thermodynamics, irreversible thermodynamics, and kinetics. Of these, kinetics provides an easy link to the microscopic description via its molecular models. The thermodynamic theories are also connected to a microscopic interpretation through statistical thermodynamics or direct molecular dynamics simulation. Statistical thermodynamics is also outlined in this section when discussing heat capacities, and molecular dynamics simulations are introduced in Sect 1.3.8 and applied to thermal analysis in Sect. 2.1.6. The basics, discussed in this chapter are designed to form the foundation for the later chapters. After the introductory Sect. 2.1, equilibrium thermodynamics is discussed in Sect. 2.2, followed in Sect. 2.3 by a detailed treatment of the most fundamental thermodynamic function, the heat capacity. Section 2.4 contains an introduction into irreversible thermodynamics, and Sect. 2.5 closes this chapter with an initial description of the different phases. The kinetics is closely link to the synthesis of macromolecules, crystal nucleation and growth, as well as melting. These topics are described in the separate Chap. 3. 

A sufficiently regular, flexible linear macromolecule, crystallized from the mobile random state, will always crystallize first in a chain-folded macroconformation. 

First, these simulations can handle large systems, are several orders of magnitude faster (and cheaper) than quantum-based calculations, and can be used for studying condensed-phase molecules, macromolecules, crystal morphology, inorganic and organic interfaces, and so on. 

Tel. 301-975-2208, fax 301-926-0416, e-mail rdj3 enh.nist.gov Thermodynamic data for almost 5000 gas phase compounds. Estimation of struaures drawn into program using Benson s additivity rules. IVTANTHERMO database with enthalpies of formation and other thermodynamic properties for 2300 substances. NIST/NASA/CARB Biological Macromolecule Crystallization Database with crystal growth conditions. PCs. 

Macromolecule Crystal system Space group Mol. helix Unit cell axes Unit cell angles No. units Pc (gcm-3)... 

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