The structure of partially expanded erythrocyte spectrin

1989 ◽  
Vol 47 ◽  
pp. 244-245
Author(s):  
Amy M. McGough ◽  
Robert Josephs
Keyword(s):  
Ionic Strength ◽  
Elastic Properties ◽  
Cell Biology ◽  
Unsolved Problem ◽  
Unit Area ◽  
Red Cell ◽  
Two Dimensional ◽  
Dimensional Network ◽  
End Distance ◽  
Cytoplasmic Side

In vivo the red cell suffers elastic deformation during its turbulent passage through the vasculature. Although the physical process responsible for the cell’s elasticity is still unknown, it is generally regarded as being a property of the erythrocyte skeleton. The skeleton, a two-dimensional network located on the cytoplasmic side of the membrane is composed of dodecamers of actin interconnected by spectrin molecules. Understanding the elastic properties of the skeleton in terms of the molecular properties of its component proteins is a major unsolved problem in red cell biology. Our work has focused on spectrin since it alone, of the skeleton proteins, appears to be able to undergo the reversible changes in structure necessary to account for the elastic properties of the red cell.Spectrin is highly alpha-helical and highly charged. Consequently the molecule can reversibly expand or condense in response to changes in ionic strength. Spectrin forms tetramers which are 2000 Å long when fully extended. The conformation actually assumed by spectrin in the cell is not known; however, calculations based on the number of molecules per unit area of membrane indicate that in the erythrocyte the average end to end distance of the molecule is only 700 Å.

scholarly journals Random Assignment Problems on 2d Manifolds

2021 ◽  
Vol 183 (2) ◽  
Author(s):  
D. Benedetto ◽  
E. Caglioti ◽  
S. Caracciolo ◽  
M. D’Achille ◽  
G. Sicuro ◽  
...  
Keyword(s):  
Assignment Problem ◽  
Unit Area ◽  
Constant Term ◽  
Beltrami Operator ◽  
Explicit Calculation ◽  
Dimensional Manifold ◽  
Two Dimensional ◽  
Random Assignment ◽  
Assignment Problems ◽  
Theoretical Formulation

AbstractWe consider the assignment problem between two sets of N random points on a smooth, two-dimensional manifold $$\Omega $$ Ω of unit area. It is known that the average cost scales as $$E_{\Omega }(N)\sim {1}/{2\pi }\ln N$$ E Ω ( N ) ∼ 1 / 2 π ln N with a correction that is at most of order $$\sqrt{\ln N\ln \ln N}$$ ln N ln ln N . In this paper, we show that, within the linearization approximation of the field-theoretical formulation of the problem, the first $$\Omega $$ Ω -dependent correction is on the constant term, and can be exactly computed from the spectrum of the Laplace–Beltrami operator on $$\Omega $$ Ω . We perform the explicit calculation of this constant for various families of surfaces, and compare our predictions with extensive numerics.

scholarly journals Crystal structure of 2-nitro-N-(5-nitro-1,3-thiazol-2-yl)benzamide

2014 ◽  
Vol 70 (12) ◽  
pp. o1252-o1252 ◽  
Author(s):  
Rodolfo Moreno-Fuquen ◽  
Diego F. Sánchez ◽  
Javier Ellena
Keyword(s):  
Crystal Structure ◽  
Hydrogen Bonds ◽  
Title Compound ◽  
Dihedral Angles ◽  
Two Dimensional ◽  
Compound C ◽  
Dimensional Network ◽  
Benzene Rings ◽  
The Mean ◽  
Amide Fragment

In the title compound, C10H6N4O5S, the mean plane of the non-H atoms of the central amide fragment C—N—C(=O)—C [r.m.s. deviation = 0.0294 Å] forms dihedral angles of 12.48 (7) and 46.66 (9)° with the planes of the thiazole and benzene rings, respectively. In the crystal, molecules are linked by N—H...O hydrogen bonds, forming chains along [001]. In addition, weak C—H...O hydrogen bonds link these chains, forming a two-dimensional network, containingR44(28) ring motifs parallel to (100).

Poly[[μ2-1,3-bis(pyridin-4-yl)propane](μ3-1,4-phenylenediacetato)cadmium]

2012 ◽  
Vol 68 (2) ◽  
pp. m34-m36 ◽  
Author(s):  
Dong Liu
Keyword(s):  
Title Complex ◽  
Point Of View ◽  
Solvothermal Reaction ◽  
Dimensional Chain ◽  
Two Dimensional ◽  
One Dimensional ◽  
Connected Network ◽  
Dimensional Network

Solvothermal reaction between Cd(NO3)2, 1,4-phenylenediacetate (1,4-PDA) and 1,3-bis(pyridin-4-yl)propane (bpp) afforded the title complex, [Cd(C10H8O4)(C13H14N2)]n. Adjacent carboxylate-bridged CdIIions are related by an inversion centre. The 1,4-PDA ligands adopt acisconformation and connect the CdIIions to form a one-dimensional chain extending along thecaxis. These chains are in turn linked into a two-dimensional network through bpp bridges. The bpp ligands adopt ananti–gaucheconformation. From a topological point of view, each bpp ligand and each pair of 1,4-PDA ligands can be considered as linkers, while the dinuclear CdIIunit can be regarded as a 6-connecting node. Thus, the structure can be simplified to a two-dimensional 6-connected network.

scholarly journals 6-Amino-3-methyl-4-(3,4,5-trimethoxyphenyl)-2,4-dihydropyrano[2,3-c]pyrazole-5-carbonitrile

2014 ◽  
Vol 70 (8) ◽  
pp. o875-o876 ◽  
Author(s):  
Naresh Sharma ◽  
Goutam Brahmachari ◽  
Bubun Banerjee ◽  
Rajni Kant ◽  
Vivek K. Gupta
Keyword(s):  
Hydrogen Bonds ◽  
Benzene Ring ◽  
Title Compound ◽  
Pyrazole Ring ◽  
Ring System ◽  
Boat Conformation ◽  
Two Dimensional ◽  
Compound C ◽  
Dimensional Network ◽  
Centroid Distance

In the title compound, C17H18N4O4, the dihedral angle between the benzene ring and 2,4-dihydropyrano[2,3-c]pyrazole ring system is 89.41 (7)°. The pyran moiety adopts a strongly flattened boat conformation. In the crystal, molecules are linked by N—H...N, N—H...O, C—H...N and C—H...O hydrogen bonds into an infinite two-dimensional network parallel to (110). There are π–π interactions between the pyrazole rings in neighbouring layers [centroid–centroid distance = 3.621 (1) Å].

Metal-Betaine Interactions.XIV. Silver(I) 3-Carboxylato-1-pyridinioacetate Monohydrate, [Ag{C5H4(COO)NCH2.COO}]n.nH2O

1991 ◽  
Vol 44 (12) ◽  
pp. 1783 ◽  
Author(s):  
XM Chen ◽  
TCW Mak
Keyword(s):  
Oxygen Atom ◽  
Water Molecule ◽  
Lattice Water Molecule ◽  
Membered Ring ◽  
Zigzag Chain ◽  
Two Dimensional ◽  
Metal Centre ◽  
Lattice Water ◽  
Dimensional Network ◽  
Tetrahedral Environment

The complex silver(I) 3-carboxylato-1-pyridinioacetate monohydrate, [Ag{C5H4(COO)NCH2.COO}]n.nH2O, crystallizes in space group P21/c (No. 14), with Z-4, a 12.233(6), b 5.049(1), c 14.418(7)Ǻ, and β 94.96(4)°; the structure was refined to RF -0.057 for 1721 observed [I ≥ 3σ(I)] Mo Kα data. The silver(I) atom is coordinated by four carboxylato oxygen atoms in a distorted tetrahedral environment [Ag-O 2.284(5)-2.570(5)Ǻ]. The tridentate acetato group bridges the Ag1 atoms into a zigzag chain featuring an uncommon [Ag2( carboxylato -O,O′)(carboxylato-μ-1,1-O)] six- membered ring, and the coordination sphere about each metal centre is completed by the unidentate aromatic carboxylato group, resulting in a two-dimensional network in the solid. The lattice water molecule forms hydrogen bonds with the uncoordinated oxygen atom of the aromatic carboxylato group [2.755(9)Ǻ] and the coordinated oxygen atom of the acetato group [2.936(9)Ǻ].

scholarly journals 2-Amino-3-carboxypyridinium perchlorate

2012 ◽  
Vol 68 (6) ◽  
pp. o1601-o1602 ◽  
Author(s):  
Fadila Berrah ◽  
Sofiane Bouacida ◽  
Hayet Anana ◽  
Thierry Roisnel
Keyword(s):  
Hydrogen Bonds ◽  
Three Dimensional ◽  
Two Dimensional ◽  
Asymmetric Unit ◽  
Dimensional Network

The asymmetric unit includes two crystallographically independent equivalents of the title salt, C6H7N2O2 +·ClO4 −. The cations and anions form separate layers alternating along the c axis, which are linked by N—H...O, O—H...O and C—H...O hydrogen bonds into a two-dimensional network parallel to (100). Further C—H...O contacts connect these layers, forming a three-dimensional network, in which R 4 4(20) rings and C 2 2(11) infinite chains can be identified.

scholarly journals Bis(2-methylpiperidinium) naphthalene-1,5-disulfonate

2012 ◽  
Vol 68 (6) ◽  
pp. o1733-o1733
Author(s):  
Qian Xu
Keyword(s):  
Hydrogen Bonds ◽  
Two Dimensional ◽  
Asymmetric Unit ◽  
Dimensional Network ◽  
Molecular Salt

In the structure of the title molecular salt, 2C6H14N+·C10H6O6S2 2−, the asymmetric unit consists of one 2-methylpiperidinium cation and one-half of a naphthalene-1,5-disulfonate anion; the anion lies across a centre of symmetry. In the crystal, the cations and anions are linked through N—H...O hydrogen bonds, forming a two-dimensional network.

scholarly journals N-(3-Chloro-1H-indazol-5-yl)-4-methoxybenzenesulfonamide

2013 ◽  
Vol 69 (11) ◽  
pp. o1632-o1632
Author(s):  
Hakima Chicha ◽  
El Mostapha Rakib ◽  
Latifa Bouissane ◽  
Mohamed Saadi ◽  
Lahcen El Ammari
Keyword(s):  
Hydrogen Bonds ◽  
Benzene Ring ◽  
Dihedral Angle ◽  
Title Compound ◽  
Two Dimensional ◽  
Common Edge ◽  
Compound C ◽  
Dimensional Network ◽  
The Common ◽  
The Mean

In the title compound, C14H12ClN3O3S, the fused five- and six-membered rings are folded slightly along the common edge, forming a dihedral angle of 3.2 (1)°. The mean plane through the indazole system makes a dihedral angle of 30.75 (7)° with the distant benzene ring. In the crystal, N—H...O hydrogen bonds link the molecules, forming a two-dimensional network parallel to (001).

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