Acta Crystallographica

Arene complexes of Platinum Group Metals (PGM) show various biological effects and there are several promising anticancer drug candidates in this class of compounds. Synergism of biological activity is foreseen when anciliary ligands such as amino acid derivatives or other bioligands are incorporated into the complexes. A series of Ru(II), Os(II), Rh(III) and Ir(III) complexes were studied and interesting kinetic/equilibrium/structural properties could be revealed [1-3]. According to our latest results presented here the N-acetylcysteine complex of the [(η6-Ar)Ru]2+ core (Ar = p-cymene) is a dimer showing bridging thiolate and chloride cordination (Figure 1, a) while a monomeric complex was formed with [S, COO–,NH2] coordination for S-methyl-cysteine when the counter ion is nitrate (Figure 1, b). With methionine an analogous compound was formed (Figure 1, c). Supramolecular analysis of the complexes indicates competing steric/Coulombic/van der Waals interactions and hydrogen bonds. X-ray diffraction and spectroscopic analysis revealed the structure of the complexes both in solution and in the solid state and also support kinetic/equilibrium findings. Acknowledgement: The research was supported by the EU and co-financed by the European Social Fund under the project ENVIKUT (TÁMOP-4.2.2.A-11/1/KONV-2012-0043). The work was supported by the Hungarian Scientific Research Fund (OTKA K76142), too. P.B. thanks members of the EU COST Action CM1105 for motivating discussions. G.B. acknowledges the support of the Bolyai János Scholarship of the Hungarian Academy of Sciences.

LBL-10154~ Preprint Submitted to Acta Crystallographica COMMENTS ON 11 HIGH-RESOLUTION IMAGES OF !3 11 ALUMINAS Lutgard C. De Jonghe November 1979 TWO-WEEK LOAN COPY This Is a which may be For a personal Circulating two weeks. copy~ Tech. Info. Division~ Ext. 6782. Prepared for the U.S. Department of Energy under Contract W-7405-ENG-48

The results of theoretical and experimental study are presented for the question of how the X-ray multiple diffraction in a silicon single crystal influences the interference fringes of section topography for the 400 reflection in the Laue case. Two different cases of multiple diffraction are discovered for zero and very small values of the azimuthal angle for the sample in the form of a plate with the surface normal to the 001 direction. The cases are seen on the same topogram without rotation of the crystal. Accurate computer simulations of the section topogram for the case of X-ray multiple diffraction are performed for the first time. It is shown that the structure of interference fringes on the section topogram in the region of multiple diffraction becomes more complicated. It has a very sharp dependence on the azimuthal angle. The experiment is carried out using a laboratory source under conditions of low resolution over the azimuthal angle. Nevertheless, the characteristic inclination of the interference fringes on the tails of the multiple diffraction region is easily seen. This phenomenon corresponds completely to the computer simulations.

Le compose du titre cristallise dans C2 avec affinement jusqu'a 0,049. Le complexe est constitue d'anion [Gd(NO 3 ) 6 ] 3− de symetrie 2 et de deux types de cations [Gd(NO 3 ) 2 (18-crown-6)] + , l'un en position speciale de symetrie 2, l'autre en position generale. Ces trois ions etant dans le rapport 1:1:2

Crk associated substrate (Cas) is an adaptor protein that becomes phosphorylated upon integrin signaling and influences regulation of cell processes such as migration, proliferation and survival. It consists of multiple domains and regions that can interact with several signaling proteins involved in different signaling pathways. Cas was first discovered as a highly phosphorylated protein in v-Src and v-Crk transformed cells, showing involvement of this protein in cell transformation High level of Breast cancer antiestrogen resistance protein (BCAR-1), a homologue to Cas has shown to correlate with rapid reoccurrence of breast cancer and also create resistance towards Tamoxifen, the widely used medicine for receptor positive breast cancer patients. We have defined boundaries of two regions of Cas termed serine rich region (SRR) and Src binding domain (SBD) respectively and have isolated these segments for biochemical and structural studies. The structure of the serine rich part of Cas has been determined by NMR spectroscopy and reveals a four-helix bundle with unusually long loops. The 14-3-3 protein binds to Cas in a phospho-serine dependent manner and our study suggests that the binding site is located between two helices. The SH2-SH3 domain of a Src family kinase, Lck has also been crystallized in complex with a nine residue long peptide corresponding to the region in Cas that binds to SH2 domains. The structure of this complex has been solved at 2.7A and shows that Cas binds Src family kinases (SFK) with high affinity suggesting a specific interaction between these two molecules. The biochemical studies on the specific binding site of these molecules show that SFK can bind to any of the phosphorylated tyrosines on the SH2 binding domain of Cas and only one phospho-tyrosine is enough to establish the binding. This binding assay does also indicate that SH3 binding domain of Cas is not essential for SFK binding.

Report of a workshop on the use of statistical validators in protein X-ray crystallography

Given a description of the stacking statistics of layered close-packed structures in the form of a hidden Markov model, analytical expressions are developed for the pairwise correlation functions between the layers. These may be calculated analytically as explicit functions of model parameters or the expressions may be used as a fast, accurate and efficient way to obtain numerical values. Several examples are presented, finding agreement with previous work as well as deriving new relations.