Molecular Replacement Studies of Cucurmosin from Cucurbita Moschata:Structure Homology with Trichosanthin

High diffraction quality crystals of cucurmosin, a type I ribosome inactivating protein isolated from the sarcocarp of Cucurbita moschata (pumpkin), have been grown under newly optimised conditions. With in-house rotating anode X-ray source, these crystals diffract to 1.65 ?resolution which is much higher than that of the previously reported crystals that diffracted only to 3 ?resolution. The crystals belong to space group P212121 with cell parameters a = 41.5, b = 58.4 and c = 99.3 . Molecular replacement studies indicate that the cucurmosin structure is homologous to trichosanthin. The initial structural model has been obtained and the model fitting/ refinement is in progress.

EXACT SOLUTION FOR FINITE DEFORMATION PROBLEMS OF CANTILEVER BEAM WITH VARIABLE SECTION UNDER THE ACTION OF ARBITRARY TRANSVERSE LOADS

This paper deals with finite deformation problems of cantilever beam with variable sec- tion under the action of arbitrary transverse loads.By the use of a method of variable replacement, the nonlinear differential equation with varied coefficient for the problem can be transformed into an equation with variable separable.The exact solution can be obtained by the integration method. Some examples are given in the paper,and the results of these examples show that this exact solution includes the existing solutions in references as special cases.

Crystal Structure of Crotin Ⅱ at 2.5 Resolution

Crotin Ⅱ is one of the ribosome inactivating proteins (RIPs). It belongs to RNA hydrolase. The crystals of crotin Ⅱ are hexagonal with a=b= 94. 62, c=28. 44 A, space group P61, Mr= 14900 Da. The structure was solved by molecularreplacement methed using the molecular structure of RNase T1 as a search model andrefined to R= 0. 25 for the reflections within 10- 2. 5 A resolution range. The refinedmodel cotains one α-helix, one two-strand antiparallel β-sheet and one five-strand an-tiparallel β-sheet. Four conservative residues His47, Glu77, Arg102 and His117 gathering in the cleft of the structure form the possible active site of crotin Ⅱ.

Discrete element method simulation of granular materials considering particle breakage in geotechnical and mining engineering:A short review

Discrete element method(DEM)-based simulations are crucial for bridging macro and micro research,particularly owing to the limitations of experimental methods.This paper reviews the simulation techniques used for particle breakage in DEM,summarizes the research status,and discusses pertinent issues to outline future prospects for particle breakage simulation.Fragment replacement method(FRM)and bonded particle method(BPM)are widely used to simulate particle breakage based on DEM.In BPM models,sub-particle size selection,particle cluster generation mode,and bonding parameters are crucial considerations.Although BPM can simulate the breakage of particles with complex shapes,it cannot re-simulate them,posing difficulties in coordinating calculation load and simulation accuracy.For FRM,the fragment replacement mode and particle breakage criteria are critical.The number and size of replacement particles are difficult to match with actual conditions,and ensuring mass conservation is significantly challenging.Although the initial computational load in FRM is relatively low,it increases significantly as the simulation progresses.To address these issues,we propose a simulation method that integrates BPM and FRM,allowing sub-particle breakage in BPM to be realized by FRM.

Studies on the Crystal Structure of [L-Met]^(B0) Bovine Insulin at 3.0 Resolution

Based on the crystal symmetry of [L-Met]^(B0) bovine insulin (LMBBI) and the fundamental theory of the molecular packing method, the scheme for the determination of the position and orientation of the molecules by only using one-dimensional rotation and one-dimensional translation was chosen to be used,and therefore the calculation of the rotation function of the molecular replacement method and the refinement of the rotational and translational parameters by using the R-factor search method were simplified greatly. After the preliminary refinement by using the macromolecular rigid body refinement technique, the molecular model was further refined and adjusted by using the energy-minimizing stereochemical-restrained least squares refinement technique assisted by the manual revision on the difference Fourier maps.The L-Met residues on the N-termlnus of the B-chain appeared clearly on the final electron density map.