Crystal Structure of Monoclonal 6B5 Fab Complexed with Phencyclidine

The crystal structure of monoclonal antibody (mAb) 6B5 Fab fragment complexed with 1-(1-phenylcyclohexyl)piperidine (PCP or phencyclidine) was determined at 2.2-A resolution. 6B5 was originally produced from a mouse immunized with a phencyclidine analogue hapten 5-[N-(1'phenylcyclohexyl)amino]pentanoic acid conjugated to bovine serum albumin. This mAb was selected for further study because of its high affinity (Kd = 2 x 10(-9) M/liter) for PCP and usefulness in reversing PCP-induced central nervous system toxicity in laboratory animals. The dominant feature of the 6B5 Fab.PCP complex is the deep binding site and hydrophobic nature of the interaction. The ligand binding pocket of 6B5 Fab has numerous aromatic side chains, as compared with other known Fab structures. The most notable feature of the binding site is a Trp at position 97H (H-chain), and the side chain of this residue appears to act as a hydrophobic umbrella on the ligand in the antigen binding pocket. There are only two other known Fabs found with a Trp at the 97H position in complementarity determining region (CDR) H3, but they do not play a major role in the interaction with their respective antigens; in both Fab TE33 and R6.5 the Trp 97H side chain is positioned away from the bound antigen. Comparison of the CDR residues of 6B5 with other Fab structures with similar CDR sizes and amino acid compositions reveals a number of important patterns of residue substitutions that appear to be critical for specific PCP ligand interactions

Tactical and Strategic Communication Network Simulation and Performance Analysis

We describe a framework for the efficient modeling and performance evaluation of large networks consisting of mixture of strategic and tactical components. The method emphasizes hierarchical, layered techniques that are fed parametric models at the lower level. In addition to the algorithmic structure, and some initial algorithms we describe an object oriented software architecture that is under development to support these algorithmic methods in a distributed environment

Party behaviour in the parliamentary arena: the case of the Korean National Assembly

This article investigates the nature of party behaviour in the legislative arena in a developing democracy by undertaking a spatial analysis of voting in the Korean National Assembly. We discover the main dimensions of politics in the Korean parliament and look at how KNA members' ideological preferences, regional interests and the shift from divided to unified government shapes relations between parties in this chamber. We find that party behaviour in the KNA is primarily ideologically based around a 'progressive-conservative' dimension of South Korean politics. However, we find that the geopolitical element of the progressive-conservative divide in Korean politics is more salient in the KNA than the socio-economic (left-right) element. We also find more division between the parties in the 17th KNA than in the 16th KNA, but this had less to do with ideological splits than the fact that the main progressive party (Uri) held the presidency and a majority in the parliament for the first time