The crystal structure of horse met-myoglobin - I. General features: the arrangement of the polypeptide chains

The preliminary results of an X-ray study of crystalline horse met-myoglobin are described. This protein crystallizes in the monoclinic space-group P2 1 with two molecules in general positions in the unit cell. The optical properties of the crystals show that the haem groups are parallel and lie approximately in the plane containing b and the internal bisector of β. a and c Patterson projections contain ridges of high vector density perpendicular to b and 15*4A apart; it is deduced that in real space the contents of the cell are arranged in pronounced layers of alternately high and low electron density, also perpendicular to b and 15*4 A apart. The b projections also exhibit rods of high vector density, 9*5 A apart and inclined at 20° to a . These rods are identified as the vector equivalents of the polypeptide chains, which thus run parallel to [20T] and 9*5 A apart. A Patterson projection along [20T] shows the rods well-resolved and in end-on view; by making certain plausible assumptions a Fourier projection has been made along the same direction. During shrinkage the cell dimensions change in such a way that the inter-chain distance alters very little; it is deduced that the molecules have flat sides parallel to (102) and that the liquid of crystallization is situated mainly on their [20T] faces. During shrinkage liquid is withdrawn and the molecules slide past one another along their flat sides. It is not possible to determine the whole shape of the molecule unequivocally; the most plausible model is a platelet built of four parallel co-planar lengths of chain each 54 A long (see figure 13). There are striking analogies between the structures of myoglobin and of horse haemoglobin. The type of chain folding seems to be the same in the two proteins, and probably the same as in a-keratin; and it may be that myoglobin has a structure analogous to that of one of the four layers of which haemoglobin is believed to be built up, the molecular weights of the two proteins being in the ratio 1:4.

1987 ◽  
Vol 65 (12) ◽  
pp. 2830-2833 ◽  
Author(s):  
David M. McKinnon ◽  
Peter D. Clark ◽  
Robert O. Martin ◽  
Louis T. J. Delbaere ◽  
J. Wilson Quail

3,5-Diphenyl-1,2-dithiolium-4-olate (1) reacts with aniline to form 1-phenylimino-2-phenylamino-3-phenylindene (3a). Under suitable conditions, 6-phenylbenzo[b]indeno[1,2-e]-1,2-thiazine is also formed. These structures are confirmed by alternative syntheses. The molecular structure of 3a has been determined by single crystal X-ray diffraction. Compound 3a crystallizes in the monoclinic space group C2/c with unit cell dimensions a = 20.777(3) Å, b = 6.130(3) Å, c = 31.327(3) Å, 3 = 99.59(1)°, and Z = 8. The structure was solved by direct methods and refined by least squares to a final R = 0.055. The molecular structure of 3a shows the three phenyl containing substituents to have the planes of their ring systems tilted between 40° and 60° from the plane of the indene system due to steric repulsions.


1987 ◽  
Vol 40 (6) ◽  
pp. 1131 ◽  
Author(s):  
CHL Kennard ◽  
G Smith ◽  
T Hari

The crystal structure of the herbicide acifluorfen (5-[(2-chloro-4-trifluoromethyl)]phenoxy-2- nitrobenzoic acid] has been determined by X-ray diffraction and refined to a residual of 0.051for 1124 observed reflections. Crystals are monoclinic, space group C2/c with cell dimensions a 26.848(7), b 8 .O29(2), c 19 .Ol4(6) �, ,R l34.72(2)� and Z 8. The molecules form centrosymmetric hydrogen-bonded cyclic dimers [O---0, 2.637(7) �] with the carboxylic acid group and the phenoxy group synclinally related to the first phenyl ring while the nitro substituent isessentially coplanar with the ring.


1975 ◽  
Vol 53 (13) ◽  
pp. 1949-1957 ◽  
Author(s):  
Roderic J. Restivo ◽  
Abraham Costin ◽  
George Ferguson ◽  
Arthur J. Carty

Copper(I) perchlorate, nitrate, and acetylacetonate complexes of the types Cu(triphos)ClO4 (triphos = CH3C(CH2PPh2)3), Cu(Cy3P)2ClO4 (Cy3P = P(C6H11)3), Cu(triphos)NO3, Cu(Cy3P)2(HFac)(HFac = hexafluoroacetylacetonate), and Cu (Cy3P)2(TtFac) (TtFac = thienyltrifluoroacetylacetonate) have been synthesized by reduction of the corresponding perchlorate, nitrate, and acetylacetonates with tertiary phosphines. Infrared spectra indicate the presence of monodentate perchlorate groups in Cu(triphos)ClO4 and in Cu(Cy3P)2ClO4 and the crystal structure of the latter has been determined by a three-dimensional X-ray analysis using diffractometer data. The crystals are monoclinic, space group C2/c, with cell dimensions a = 18.159(6), b = 9.493(2), c = 22.182(3) Å, and β = 95.41(2)° and four molecules per unit cell. The structure was refined by block-diagonal least squares methods to a final R of 0.051 for 2617 reflections using anisotropic thermal parameters for the nonhydrogen atoms. The structure consists of discrete Cu(Cy3P)2ClO4 molecules with symmetry C2 separated by normal van der Waals distances. The copper atom is three-coordinate and the perchlorate anion is monodentate but disordered over two sites. Principal dimensions include: Cu—P 2.262(1) Å, Cu—O 2.220(7) Å, [Formula: see text][Formula: see text] and 99.8(2)°, and [Formula: see text]


1987 ◽  
Vol 65 (4) ◽  
pp. 804-809 ◽  
Author(s):  
Raj K. Chadha ◽  
Peter C. Hayes ◽  
Hassan E. Mabrouk ◽  
Dennis G. Tuck

In(SPh)3 is readily prepared by the reaction of InCl3 and NaSPh in methanol. The compound is a Lewis acid, forming 1:1 adducts with 2,2′-bipyridine, 1,10-phenanthroline, N,N,N′,N′-tetramethylethanediamine, bis(diphenylphosphino)ethane, and dimethylsulphoxide, and 1:2 adducts with pyridine, trimethylamine, and triphenylphosphine. Reaction with R4NX (X = Cl, Br, I) or similar salts gives R4N[XIn(SPh)3] salts, which are 1:1 electrolytes. The structure of Ph4P[BrIn(SPh)3] has been determined by X-ray methods. The crystals are monoclinic, space group P21/c, with cell dimensions a = 9.964(3) Å, b = 13.477(3) Å, c = 30.359(7) Å, α = 98.30(2)°, Z = 4, R = 0.0622 for 2924 unique observed reflections. The anion has distorted tetrahedral symmetry in the InBrS3 kernel, with In—Br = 2.527(2) Å, and In—S(av) = 2.450 Å. The vibrational spectra of In(SPh)3 and its derivatives in the region 500–200 cm−1 are discussed.


2005 ◽  
Vol 3 (4) ◽  
pp. 780-791 ◽  
Author(s):  
Aamer Saeed ◽  
Masood Parvez

Abstract1-(4-Chlorophenyl)-3-(4-methylbenzoyl)thiourea was synthesized and characterized by IR,1H and 13C NMR, mass spectroscopy and the elemental analysis. The crystal structure was confirmed from single crystal X-ray diffraction data. It crystallizes in the monoclinic space group P21/c with unit cell dimensions a=12.038(3), b=6.330(6), c=18.912(5) Å and β=100.32(3)°. There is a strong intramolecular hydrogen bond of the type N−H...O, with distance N1...O1=2.659(3) Å. The structure is composed of dimers related by inversion centers. The dimers are formed by intermolecular interactions of the type N−H...S with N...S separation of 3.440(2) Å. The mass fragmentation pattern has also been discussed.


1988 ◽  
Vol 41 (9) ◽  
pp. 1353 ◽  
Author(s):  
PS Moritz ◽  
AA Diamantis ◽  
FR Keene ◽  
MR Snow ◽  
ERT Tiekink

Reaction of molar ratios of the ligands tri(2-pyridyl)amine (Py3N), or tri(2-pyridyl)-methanol (Py3COH) with [ Ru (NH3)3(OH2)3]2+ in aqueous solution produces the respective [ Ru (NH3)3(tripod)]2+ complexes. The analogous reaction with tri(2-pyridyl)methane (Py3CH) yields [ Ru (NH3)2(OH2)(Py3CH)]2+, while the reaction with the tri(2-pyridyl ) phosphine ligand produces several (unidentified) species. The N- and CH-bridged ligands appear coordinated in a tripodal manner through the three pyridine-N atoms of the ligand , whereas tri(2- pyridyl )-methanol is coordinated in an N,N′,O mode through two pyridine-N atoms and the hydroxy group of the bridge. The X-ray crystal structure of [ Ru (NH3)3(Py3COH)]Br2.H2O confirms this assignment: the complex of formula C16H24Br2N6O2Ru is monoclinic, space group P21/c, with cell dimensions a 13.916(6), b 10.300(2), c 15.910(7)Ǻ, β 111.90(3)°, and Z 4. Full-matrix least-squares refinement on 2062 reflections with 1 ≥ 2.5σ(I) converged to final R 0.030 and Rw 0.035. The coordinated OH group in the complex has a pKa of 6.5(�0.1) at 25°C (aqueous 0.1 mol dm-3 KNO3).


Crystals ◽  
2019 ◽  
Vol 9 (11) ◽  
pp. 599
Author(s):  
Jung-Seop Lee ◽  
Matthias Zeller ◽  
Shrikant Dashrath Warkad ◽  
Satish Balasaheb Nimse

N-(3-nitrophenyl)cinnamamide 1 with formula C15H12N2O3 was synthesized, and its crystal structure was determined by single-crystal X-ray diffraction analysis. Compound 1 crystallizes in the monoclinic space group P21/n with unit cell dimensions: a = 6.7810 (5) Å, b = 23.0913 (15) Å, c = 8.2079 (5) Å, V = 1282.76 (15) Å3, Z = 4, determined at 150 K with MoKα radiation. The experimental structure refined against atomic scattering factors is compared with the structure obtained using a Hirshfeld Atom Refinement (HAR) approach and Density Functional Theory (DFT) geometry optimizations.


1988 ◽  
Vol 41 (4) ◽  
pp. 597 ◽  
Author(s):  
MI Bruce ◽  
MP Cifuentes ◽  
KR Grundy ◽  
MJ Liddell ◽  
MR Snow ◽  
...  

An improved, one-pot synthesis is reported for the [Ru (dppm -P)(dppm -P, P′)(η-C5H5)]+ cation as its BF4- salt. The crystal structure of [Ru ( dppm - P)( dppm -P,P′)(η-C5H5)]+, obtained as the mixed PF6-/PO2F2- salt, has also been determined. There are few differences in dimensions between the mono- and bi-dentate dppm ligands; chelation sharply reduces the P-CH2-P angle, and one phenyl group on each phosphorus is bent away from the metal. Crystals are monoclinic, space group C2/c with unit cell dimensions a 21.743(3), b 23.594(3), c 21.352(3)Ǻ, β 110.17(1) and Z 8. The structure was refined by a full-matrix least-squares procedure to final R 0.078 and Rw 0.087 for 4490 reflections with I > 2.5σ(I).


Author(s):  
L. W. Labaw

Crystals of a human γGl immunoglobulin have the external morphology of diamond shaped prisms. X-ray studies have shown them to be monoclinic, space group C2, with 2 molecules per unit cell. The unit cell dimensions are a = 194.1, b = 91.7, c = 51.6Å, 8 = 102°. The relatively large molecular weight of 151,000 and these unit cell dimensions made this a promising crystal to study in the EM.Crystals similar to those used in the x-ray studies were fixed at 5°C for three weeks in a solution of mother liquor containing 5 x 10-5M sodium phosphate, pH 7.0, and 0.03% glutaraldehyde. They were postfixed with 1% osmium tetroxide for 15 min. and embedded in Maraglas the usual way. Sections were cut perpendicular to the three crystallographic axes. Such a section cut with its plane perpendicular to the z direction is shown in Fig. 1.This projection of the crystal in the z direction shows periodicities in at least four different directions but these are only seen clearly by sighting obliquely along the micrograph.


Author(s):  
H.-J. Cantow ◽  
H. Hillebrecht ◽  
S. Magonov ◽  
H. W. Rotter ◽  
G. Thiele

From X-ray analysis, the conclusions are drawn from averaged molecular informations. Thus, limitations are caused when analyzing systems whose symmetry is reduced due to interatomic interactions. In contrast, scanning tunneling microscopy (STM) directly images atomic scale surface electron density distribution, with a resolution up to fractions of Angstrom units. The crucial point is the correlation between the electron density distribution and the localization of individual atoms, which is reasonable in many cases. Thus, the use of STM images for crystal structure determination may be permitted. We tried to apply RuCl3 - a layered material with semiconductive properties - for such STM studies. From the X-ray analysis it has been assumed that α-form of this compound crystallizes in the monoclinic space group C2/m (AICI3 type). The chlorine atoms form an almost undistorted cubic closed package while Ru occupies 2/3 of the octahedral holes in every second layer building up a plane hexagon net (graphite net). Idealizing the arrangement of the chlorines a hexagonal symmetry would be expected. X-ray structure determination of isotypic compounds e.g. IrBr3 leads only to averaged positions of the metal atoms as there exist extended stacking faults of the metal layers.


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