MKK4 activates both JNKs and p38s. We determined the crystal structures of human non-phosphorylated MKK4 kinase domain (npMKK4) complexed with AMP-PNP (npMKK4/AMP) and a ternary complex of npMKK4, AMP-PNP and p38α peptide (npMKK4/AMP/p38). These crystal structures revealed that the p38α peptide-bound npMKK4 at the allosteric site rather than at the putative substrate binding site and induced an auto-inhibition state. While the activation loop of the npMKK4/AMP complex was disordered, in the npMKK4/AMP/p38 complex it configured a long α-helix, which prevented substrate access to the active site and αC-helix movement to the active configuration of MKK4.

Sessions 4This Bijvoet difference, however, is still small and highly accurate data collection is essential.One of the experimental difficulties using longer wavelength is the increased absorption.Therefore we have developed a crystal mounting technique to eliminate absorption by the frozen cryo-buffer around protein crystal (Kitago et al., 2005), and the practical applicability of this mounting method was examined using several novel proteins at CrKα radiation of 2.29 Å (Watanabe, 2006).In order to utilize this mounting method at the synchrotron beamlines, we made this mounting tool compatible to the standard Hampton CrystalCap.With a special magnet base for this cap, it becomes possible to mount and remount frozen crystals as the standard CrystalCap.We have tested its applicability by sending several frozen crystals to the beamline BL13B1 at NSRRC, Taiwan.This mounting method is also very useful at synchrotron beamlines to mount tiny crystals that are difficult to center because of the lens-shaped frozen buffer in the cryoloop.In this development, we also use a loop made of a polyimide film microfabricated by photolithography.

The crystal structure of Serratia protease from Serratia sp. E-15 was solved by the single isomorphous replacement method supplemented with anomalous scattering effects from both the Zn atom in the native crystal and the Sm atom in the derivative crystal, and refined at 2.0 A resolution to a crystallographic R-factor of 0.194. The enzyme consists of N-terminal catalytic and C-terminal beta-sandwich domains, as observed in alkaline protease from Pseudomonas aeruginosa IFO3080. The catalytic domain with a five-stranded antiparallel beta-sheet and five alpha-helices shares a basically common folding topology with those of other zinc metalloendoproteases. The catalytic zinc ion at the bottom of the active site cleft is ligated by His176, His180, His186, Tyr216, and a water molecule in a distorted trigonalbipyramidal manner. The C-terminal domain is a beta-strand-rich domain containing eighteen beta-strands and a short alpha-helix, and has seven Ca2+ ions bound to calcium binding loops. An unusual beta-sheet coil motif is observed in this domain, where the beta-strands and calcium binding loops are alternately incorporated into an elliptical right-handed spiral so as to form a two-layer untwisted beta-sandwich structure. The Ca2+ ions in the C-terminal domain seem to be very important for the folding and stability of the beta-sheet coil structure.

The crystal structure of the unliganded alkaline protease from Pseudomonas aeruginosa IF03080 has been determined at 2.0 A resolution by the X-ray method. The enzyme consists of N-terminal catalytic and C-terminal β-helix domains. On structural comparison between the present unliganded enzyme and structurally-known liganded enzyme, some structural changes were observed around the active site. In the unliganded enzyme, Y216 serves as the fifth ligand for the active site zinc ion. On ligand binding, Y216 may move to form a hydrogen-bond with the carbonyl oxygen of the P1 residue of a ligand peptide. D191 in the flexible loop, Y190 to D196, over the active site cleft forms hydrogen-bonds with the backbone atoms of the P1 and P2 residues of the ligand to close the entrance of the cleft. The water molecule which is the fourth ligand for the zinc ion is replaced by the carbonyl oxygen of the P1 residue. These structural changes around the active site may reflect the substrate-binding mode during the enzymatic reaction.

The structure of cytochromeb562fromEscherichia colihas been refined at 1.4 Å resolution against X-ray data collected on a Picker four-circle diffractometer. The triclinic unit cell parameters area=33.68 Å,b=50.48 Å,c=32.67 Å, α=102.51°, β=86.56° and γ=107.01° and there are two molecules in the asymmetric unit. A total of 138 cycles of restrained crystallographic refinement using the program PROLSQ were augmented at intermediate stages by two cycles of simulated annealing refinement using X-PLOR. The final crystallographicR-factor is 16.4% for data in the resolution range 6.0 Å to 1.4 for a model containing 1650 protein atoms, 86 heme atoms, 165 water molecules and four sulfate anions. The root-mean-square deviations from ideal bond lengths and angles are 0.012 Å and 2.0°, respectively. Each molecule consists of a bundle of four α-helices arranged in a simple up-dooown-up-down manner with a non-covalently bound heme group inserted between the first and fourth helices. In addition, there is a very short 310helix in the 15-residue loop connecting the first and second pairs of helices. The two independent molecules show r.m.s. differences of 0.30 Å for main-chain atoms and 0.88 Å for all atoms. A detailed comparison with the structurally similar cytochromec° fromRhodospppirulum molishianumis presented. In addition, the titration behavior of cytochromeb562in solution is discussed in terms of its molecular structure.

(I) 1/2C38H30N2O2.C3H6O, M(r) = 331.4, triclinic, P1BAR, a = 10.076 (2), b = 12.346 (3), c = 9.154 (2) angstrom, alpha = 98.90 (2), beta = 122.06 (2), gamma = 96.67 (2)-degrees, V = 926.3 (4) angstrom3, Z = 2, D(m) = 1. 185 (1) D(x) = 1. 188 Mg m-3 lambda(Cu Kalpha) = 1.5418 angstrom, mu = 0.565 mm-1, F(000) 352, T = 295 K, R = 0.055 for 2459 observed reflections. (II) C38H30N2O2.C3H6O, M(r) = 604.7, monoclinic, C2/c, a = 16.782 (2), b = 8.744(3), c = 23.386(3)angstrom, beta = 107.83(2)-degrees, V = 3267.0 (12) angstrom3, Z = 4, D(m) = 1.227 (2), D(x) = 1.229 Mg m-3, lambda(Cu Kalpha) = 1.5418 lambda, mu = 0.573 mm-1, F(000) = 1280, T = 295K, R = 0.050 for 2342 observed reflections. In both crystals, trans-3,3'-bis(diphenylhydroxymethyl)azobenzene is on a centre of symmetry, while acetone is situated at a general position in (i) and on a twofold axis in (II). Molecules in the complex are hydrogen bonded, although the scheme is different in the two crystals.

The crystal structure of the complex between the quinoprotein methylamine dehydrogenase (MADH) and the type I blue copper protein amicyanin, both from Paracoccus denitrificans, has been determined at 2.5-A resolution using molecular replacement. The search model was MADH from Thiobacillus versutus. The amicyanin could be located in an averaged electron density difference map and the model improved by refinement and model building procedures. Nine beta-strands are observed within the amicyanin molecule. The copper atom is located between three antiparallel strands and is about 2.5 A below the protein surface. The major intermolecular interactions occur between amicyanin and the light subunit of MADH where the interface is largely hydrophobic. The copper atom of amicyanin and the redox cofactor of MADH are about 9.4 A apart. One of the copper ligands, His 95, lies between the two redox centers and may facilitate electron transfer between them.

ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTEnantioselective photoreactions of cycloocta-2,4,6-trien-1-one and cycloocta-2,4-dien-1-one in their inclusion complexes with (R,R)-(-)-1,6-bis(o-chlorophenyl)-1,6-diphenylhexa-2,4-diyne-1,6-diol: mechanistic study based on x-ray crystal structure analysesTakaji Fujiwara, Nobutsugu Nanba, Kensaku Hamada, Fumio Toda, and Koichi TanakaCite this: J. Org. Chem. 1990, 55, 15, 4532–4537Publication Date (Print):July 1, 1990Publication History Published online1 May 2002Published inissue 1 July 1990https://pubs.acs.org/doi/10.1021/jo00302a014https://doi.org/10.1021/jo00302a014research-articleACS PublicationsRequest reuse permissionsArticle Views114Altmetric-Citations25LEARN ABOUT THESE METRICSArticle Views are the COUNTER-compliant sum of full text article downloads since November 2008 (both PDF and HTML) across all institutions and individuals. These metrics are regularly updated to reflect usage leading up to the last few days.Citations are the number of other articles citing this article, calculated by Crossref and updated daily. Find more information about Crossref citation counts.The Altmetric Attention Score is a quantitative measure of the attention that a research article has received online. Clicking on the donut icon will load a page at altmetric.com with additional details about the score and the social media presence for the given article. Find more information on the Altmetric Attention Score and how the score is calculated. Share Add toView InAdd Full Text with ReferenceAdd Description ExportRISCitationCitation and abstractCitation and referencesMore Options Share onFacebookTwitterWechatLinked InRedditEmail Other access optionsGet e-AlertscloseSupporting Info (1)»Supporting Information Supporting Information Get e-Alerts

Crystal structures of the stable and a metastable phases of 2,4-bis(trichloromethyl)-benzo-1,3-dioxine-6-carboxylic acid (TMB-COOH) and 2,4-bis(trichloromethyl)-benzo-1,3-dioxine-6-amine (TMB-NH 2 ) were determined at room temperature. Crystal data are as follows; TMB-COOH (stable): monoclinic, space group C 5 2h -P2 1 /n, a = (1052.6 ± 0.2) pm, b = (2582.2 ± 0.4) pm, c = 598.7 ± 0.3) pm, β = 99.86° ± 0.02°, R = 0.053; TMB-COOH (metastable): monoclinic,space group C 5 2h -P2 1 / c , a = (577.5 ± 0.5) pm, b = (2087.2 ± 1.1) pm, c = (1318.6 ± 0.7) pm, β = 91.98° ± 0.06°, R = 0.098; TMB-NH 2 : orthorhombic, space group C 9 2v -Pna2 1 , a = (2539.0 ± 0.2) pm, b = (1005.1 ± 0.1) pm, c = (566.7 ± 0.1) pm, R = 0.049. Disorder of hydrogen atom in the O  H ··· O hydrogen bond system was found for the cyclic dimers of TMB-COOH in both phases. Judging from the molecular structures determined, chloral hydrate and 4-substituted phenols seem to react in a stereospecific way to give a single conformer found in these crystals. The 35 Cl NQR spectra of TMB-COOH, TMB-NH 2 and related compounds were measured in the range 77 ≦ T/K ≦ 400. The temperature dependence of the NQR spectra showed that the potential barrier hindering the reorientation of the group is considerably different for the two nonequivalent CCl 3 groups in a molecule. Atom-atom potential calculations based on the crystal data showed that the difference is of intermolecular nature. The NQR frequencies calculated from the orbital populations obtained by the CNDO/2 MO method are consistent with the observed one.

A new natural cyclopentenone derivative has been isolated from the potato culture solution of Phoma wasabiae, and its structure was determined to be (5S*)-5-acetyl-3,5-dimethoxy-2-methyl-(4R*)-4-[(2R*)-2-methylbutanoyl]-2-cyclopenten-1-one by spectroscopic and single crystal X-ray diffraction analyses.

Abstract Selective inclusion of the diequatorial isomer of 3,5-dimethylcyclohexanone and the triequatorial isomer of 3,5-dimethylcyclohexanol by 1,1,6,6-tetraphenylhexa-2,4-diyne-1,6-diol was observed. The crystal structure of these complexes was studied.

Abstract Of two tautomers of 2-mercapto substituted tropone, 2-mercaptotropone and 2-hydroxytropothione, the former is isolated as a 2:1 complex with 1,1,6,6-tetraphenylhexa-2,4-diyne-1,6-diol, and infrared and electronic absorption spectra of the complex are reported. X-Ray crystal structural study shows that the 2-mercaptotropone in the complex has no bond alternation and then has a delocalized π-electron system.

The first direct X-ray crystal structure determination of a 1:2 adduct obtained by Diels–Alder reaction of [2.2]paracyclophane and N-methylmaleimide is reported, establishing the structure arising from 4,7- and 13,16-additions.

The X-ray crystallographic analysis of silver(I)-13,14-benzo-1,4,8,11-tetrathiacydopentadec-13-ene picrate (Ag-Bz-TTCP-Pic) was carried out. The molecular structure of its complex cation is discussed in connection with its solvent extraction behavior. The Ag-Bz-TTCP cation complex is not the simple 1:1 monomer complex cation, [Ag(bz-ttcp)]+ but the 2:2 dimeric complex cation, [Ag2(bz-ttcp)2]2+. Each silver(I) ion has the coordination number 5 and binds with five sulfur atoms: four sulfur atoms in one Bz-TTCP molecule and one sulfur atom in another Bz-TTCP, to form a distorted square pyramidal configuration. Thus two silver(I) ions are sandwiched between two Bz-TTCP molecules so that they look as if they were surrounded with two cyclic polythioether rings and two benzene rings. The charge on two silver(I) ions is delocalized on the dimeric complex. Thus the formation of the ion pair complex with two picrate anions is so stabilized that silver(I) will be almost completely extracted.

Preliminary X-ray studies on Serratia protease have been carried out using crystallographic and small angle scattering techniques. The enzyme has been crystallized in three different crystalline forms by microdialysis and vapor diffusion methods using 50 mM phosphate buffer, pH 6.0, at 24 degrees C. They have orthorhombic space groups: C222(1) for one form and P2(1)2(1)2(1) for the other two forms. A small angle X-ray scattering study showed that the radius of gyration and the maximal dimension of the molecule in aqueous solution are 26.6 A and 94.5 A, respectively. The molecular weight of the enzyme was determined to be 45,000-48,000 by various physical methods.