CRYSTALLOGRAPHIC STUDIES OF THE COMPLEX OF MUNG BEAN TRYPSIN INHIBITOR WITH PORCINE TRYPSIN

The Bowman-Birk family inhibitor isolated from the mung bean can combine with porcine trypsin to form a complex at a molar ratio of 1:2. The single crystals of the complex, suitable for X-ray structural study, were obtained by using the micro-still-setting method. Initial crystallographic investigation showed that the crystals diffract to 2.7 resolution and belong to the tetragonal system. Its space group is 1422 with cell dimensions a=b=122.4 (2), c=113.4(2). The density of the crystal was 1.20g/cm~3 and the solvent constant was 36%. There is one complex molecule in a crystallographic asymmetric unit.     

CRYSTAL STRUCTURE DETERMINATION OF 4-ZINC BOVINE INSULIN AT 1.9 (?) RESOLUTION

With the isomorphous difference Fourier method and the restrained least-squares re-finement technique, the crystal structure of 4- zinc bovine insulin in space group R_3 wasdetermined. The final crystallographic residual is 0. 19 at 1. 9A resolution. Based on therefined model, the structural mechanism for prolonged action of 4- zinc insulin is discussed.     

REFINED CRYSTAL STRUCTURE OF INSULIN AT 1.8A RESOLUTION——CRYST

The structure of insulin has been refined by difference Fourier method at 1.8A resolu-tion. A set of computer programs calculating the mF_o-nF_c Fourier synthesis and the cor-rections of parameters automatically has been set up. With the programs to refine theinsulin model obtained from MIR map at 1.8A resolution for 11 cycles, the R index(R=∑|KF_o- F_c|/∑KF_o) is reduced to 0.210 from the initial value of 0.388. Duringthe refinement the stereochemistry of the insulin molecules is constantly detected andadjusted to fit the reasonable geometry. The refinement has greatly improved the structuremodel of insulin and provided more detailed structure information. On the basis of this thesystems of hydrogen bond in an insulin dimer are determined and the interaction betweenwater and insulin molecules in the crystal is investigated.     

STUDIES ON THE MUNG BEAN TRYPSIN INHIBITOR——REDUCTION AND REOXIDATION OF THE DISULFIDE BONDS OF THE LYS ACTIVE FRAGMENT

Two peptide chains A_1 and A_2 of the Lys active fragment, linked via a couple ofinter-disulfide bonds, could be separated from each other after reduction with dithiothreitoland gel filtration on Sephadex G-25. Reoxidation of the reduced peptide chain A_1 resultedin recovering the inhibitory activity with 25% yield, based on the original activity of theLys fragment. The A_1 active fragment was further purified by affinity chromatographywith immobilized trypsin. Sephadex G-25 gel filtration produced two forms of the A_1 activefragment, the major fraction being a monomer and the minor one being a dimeer with loweractivity. The results obtained offered evidence of the evolution of mung bean inhibitorfrom an ancestral single-headed inhibitor by fused gene duplication with A_2 as a connectingpeptide. The CD spectra of the Lys fragment and the reoxidized peptide chain A_1 werealso compared.     

REFINED CRYSTAL STRUCTURE OF INSULIN AT 1.8A RESOLUTION——HYDROGEN BONDS AND BOUND WATER

The hydrogen bonds in insulin fall into three cases: the helical hydrogen bonds in α- or 3_(10)helices, the non-helical one formed by polar groups of insulin itself, and the hydrogen bondsformed between insulin and water. By using the information obtained, the results of a seriesof biochemical investigations on insulin analogs related to B-chain C-terminal peptide can beinterpreted and it can also be inferred that the complex behaviours of the aggregation ofinsulin may play a protective role for the unique conformation of the molecule. Water structure also appears in the refined model. About one third of the water in anasymmetric unit is hydrogen-bonded to insulin molecules or each other, which are referred toas bound water. The polar and charged groups of insulin all show the tendencies to bind towater molecules as many as possible, which is a significant factor for the stabilization of theunique conformation of the molecule. The binding way of water molecules to insulin mole-cules is also analysed.     

CRYSTAL AND MOLECULAR STRUCTURE OF A PENTA-COOR-DINATED SILVER COMPLEX, SILVER 8-HYDROXYQUINOLINE-5-SULFONATE AgC_9H_8NO_4S

<正> AgC9H6NO4S, Mr = 332. 1, monoclinic, space group P21/c, a = 8. 292(1), b = 10. 394(2), c=10. 852(2)A, β=102. 73(1)°, V =912. 4(?)3, Z = 4, Dc = 2. 417gcm-3, λ(MoKα) = 0. 71073(?) , μ = 24. 0cm-1, F (000) = 648, final R =0. 041, Rw = 0. 047 for 1369 observed reflections. The coordination polyhedron of Ag(I) is penta-coordinated square pyramid.     

CRYSTAL AND MOLECULAR STRUCTURE OF 1，2，3，4—TETRAKIS（6‘,7’—DIMETHYL）BENZOXAZOLYL CYCLOBUTANE

<正> 1,2,3,4-Tetrakis(6',7'--dimethyl)benzoxazolyl cyclobutane was obtained by irradiation of E-l,2-bis(6',7'-dimethyl-1',3'-benzoxazolyly-2')-ethene in ethanol with a 450-watt high pressure mercury lamp. Its crystal and molecular structure has been determined by X-ray diffraction method. The crystal is triclinic, space group A with a = 7.008(2), b=9.586(1), c = 13.174(2)A,α= 104.08(1),β= 98.56(2),γ=99.97(2)°,V= 828.4A3, Mr= 636.76, (C40H36N4O4), Z =1, Dx =1.28g/cm3,μ= 0.78 cm-1 and F(OOO)=336.     

STUDIES ON DERIVATIVES OF 2, 3-DIHYDRO-4 H-1, 3, 2-BENZOXAZAPHOSPHORINE——THE DETERMINATION OF THE CRYSTAL AND MOLECULAR STRUCTURE OF 2, 3-DISUBSTITUTED-2, 3-DIHYDRO-4H-1, 3, 2-BENZOXAZAPHOSPHORIN-4-ONE (THION)-2-SULFIDE(OXIDE)

The two crystal structures of C_(17)H_(17),N_2O_2Cl_2PS (NP-8) and C_(17)H_(19)N_2O_2PS (NP-10-Ⅱ) have beendetermined by Patterson method. The crystals belong to monoclinic system with space group of P2_1/aand P2_1/n respectively. There are four molecules in the unit cell. Cell parameters: a = 26.622 (7)A, b = 7.711 (2) A., c = 9.461 (3) A, β = 94.90°(4) and a = 18.879(3) A, b = 10.199 (13) A, c = 8.948(3) A, β= 94.30°(3) for the two cells. After refinement by block diagonal matrix least squares me-thod, R factors are 0.046 for 2971 reflections of NP-8 and 0.076 for 1711 reflections of NP-10-Ⅱ. Referring to molecular structures of NP-8 and NP-10-Ⅱ spectra data have been satisfactorilycxplained. The characteristic features of the structures have been discussed.     

CRYSTAL AND MOLECULAR STRUCTURE OF A DIPHENYL SULFOXIDE COMPLEX WITH CERIUM NITRATE, Ce(N0_3)_3[(C_6H_5)_2SO]_4

<正> The title complex crystallises in the triclinic, space group PT with two formula units in a unit cell of dimensions a=11.182(4), b=14.357(5), c=17.362(6) A and α= 84.08(3)°, β=72.79(3)°, r= 69.27(2)°, Dx=1.51 g.cm-3, V=2489.6(15) A3. The final index for 6319 observed reflections is 0.0274. The Ce3+ ion is coordinated by ten oxygen atoms with Ce-O distances varying from 2.469 to 2.706 A. The three nitrate groups are all bidentate ligands.     

CYCLOADDITION REACTION OF THE AZIDO-BRIDGED CYCLOMETALLATED COMPLEX [Pd(dmba)N3]2 WITH CS2. CRYSTAL AND MOLECULAR STRUCTURE OF DI(μ, N,S-l,2,3,4-THIATRIAZOLE-5-THIOLATE)BIS[(N,N-DIMETHYLBENZYL-AMINE-C2,N)PALLADIUM(II)]

Abstract

The 1,3-dipolar cycloaddition of carbon disulfide to the coordinated azide in the cyclometal-lated compound [Pd(dmba)(N₃)]₂ (1), dmba = N,N-dimethylbenzylamine, was investigated. The compound obtained di(μ, N, S-l,2,3,4-thiatriazole-5-thiolate)-bis[(N,N-dimethylbenzylamine-C², N)palladium(II)] (2), was characterized by IR spectroscopy and X-ray diffraction. Complex (2) is dimeric with the two [Pd(N,N-dimethylbenzylamine)] moieties being connected by the two vicinal bridging N, S-l,2,3,4-thiatriazole-5-thiolate anions in a square-planar coordination for the palladium atoms.     

STUDY ON TRINUCLEAR MOLYBDENUM CLUSTER COMPOUNDS——THE CRYSTAL AND MOLECULAR STRUCTURE OF THE TWO TRINUCLEAR MOLYBDENUM CLUSTERS(C_5H_7S_2)[Mo_3(μ_3-O )(μ-X)_3(μ-OAc)_3Cl_3](X=Cl,Br)

The crystal structure of two isomorphic cluster compounds with formula (C_5H_7S_2)-[Mo_3(μ_3-O)(μ-X)_3(μ-OAc)_3Cl_3] (X=Cl for compound (Ⅰ) and compound (Ⅱ)) has been investigated by X-ray diffraction method. The parameters of two crystals are: a=10.423(1),b=17.095(4), c=14.062(7), β=97.54(4)(°); Dc=2.20gcm~(-3), D_o=2.17g cm~(-3) for compound (Ⅰ). and a=10.511(3), b=11.213(2), c=14.053(3), β=96.12(2)(°); D_c=2.52g cm~(-3), D_o=2.53gcm~(-3) for compound (Ⅱ). The space groups are P2_1/C. Z=4. The 2621 and 2548 independent reflections with I>3σ(I) were collected on a CAD-4 four-circle diffractometer by means of MoKα radiation. The crystal structures were solved by heavy atom method and refined by full-matrix least-squares technique to a final discrepancy factors of R=0.061 and 0.051 respectively. The results of investigation show that the molecule consists of the cation (C_5H_7S_2)+ and the trinuclear Mo cluster anion, the configuration of which is similar to that of (Et_4N)_2[Mo_3(μ_3-O)(μ