Neutronenkleinstwinkelstreuung an Roten Blutzellen

Neutronenstreumessungen im Kleinstwinkelbereich wurden an Roten Blutzellen vorgenommen (Gerat D11, Institut Laue-Langevin, Grenoble). Die Mesmoglichkeiten des Gerats an der Auflosungsgrenze wurden erprobt. Im Einfachstreubereich konnten die ublichen Auswerteverfahren erfolgreich verwendet werden: der Streumassenradius wurde zu 2.8 ± 0.2 μ und die Spezifische Oberflache zu 1.7 ± 0.6 μ−1 bestimmt. Im Vielfachstreubereich wurde die Spezifische Oberflache zu 1.7 ± 0.3 μ−1 ermittelt. Durch Einfuhrung des Begriffs der Streuvielfachheit lassen sich die Messungen besser einordnen. Mit den theoretischen Beugungsansatzen vonLuzzati bzw. Soule war es moglich, die Messungen in allen Streubereichen zufr…

Resonance scattering in macromolecular structure research

Resonance (or anomalous) X-ray scattering of partially ordered macromolecular structures, amorphous materials and solutions is encountered in the near edge region of X-ray absorption edges where the resonant real part f' of atomic form factors shows the strongest dispersion. The requirements of spectral brilliance in the near absorption edges can only be met by synchrotron radiation emitted from high energy electron (positron) storage rings. Resonance scattering yields three basic scattering functions. This compares to contrast variation in neutron scattering. The relations to isomorphous replacement methods of crystallography are discussed. The analysis of the basic scattering functions in…

Dynamic nuclear polarisation of biological matter

Polarised targets as used in high energy physics experiments may be of considerable interest in biological structure research using polarized neutrons. So far, this promising method has been facing difficulties in getting reasonable polarization of the target nuclei. We report on a polarized "frozen spin" target which has been prepared from an enzyme dissolved in a mixture of heavy water and deuterated propanediol doped with a completely deuterated paramagnetic radical. Clusters of 700 protons defined by the structure of lysozyme embedded in a fully deuterated matrix were polarized to 75% within an hour by 4 mm microwave irradiation in a magnetic field of 2.5 tesla at a temperature of 0.3 K…

Struktur�nderungen bei der reversiblen Denaturierung von Glukoseoxidase ausAspergillus niger

Resonant X-Ray Scattering of Biological Systems

Nearly all synchrotron radiation laboratories at high energy electron storage rings put enormous effort into the developement of resonant (anomalous) X-ray scattering techniques. So does the Hamburger Synchrotronstrahlungslabor (HASYLAB) at Hamburg. One of these intruments which is built in cooperation with the university of Mainz at the beam line A1 of the storage ring DORIS. How does the physics of resonant scattering enter into the design of the X-ray instrument.

Advances in contrast variation for macromolecular structure determination by polarized neutron scattering and anomalous dispersion of synchrotron X-rays

Contrast variation for macromolecular structure determination is usually achieved by isomorphous replacement of 1-H by 2-H (D) using small-angle neutron scattering (SANS). This is particularly easy in aqueous solvents. By adding heavy water the contrast of dissolved proteins, nucleic acids and membranes changes drastically. It is the region inaccesible to solvent molecules, which acts as a label. Measurements of the scattering intensity at three different scattering densities of a solvent yields the three basic scattering functions. The contrast dependence of the radius of gyration receives particular interest. More recently smaller labels have been used. Their dimensions are smaller than t…