A new model for packing of type-I collagen molecules in the native fibril

1981 ◽  
Vol 1 (10) ◽  
pp. 801-810 ◽  
Author(s):  
Karl A. Piez ◽  
Benes L. Trus
Keyword(s):  
Type I Collagen ◽  
Hexagonal Lattice ◽  
Three Dimensional ◽  
Equatorial Region ◽  
Type I ◽  
X Ray Diffraction ◽  
X Ray ◽  
Left Handed ◽  
Crystal Model ◽  
Collagen Molecules

A specific fibril model is presented consisting of bundles of five-stranded microfibrils, which are usually disordered (except axially) but under lateral compression become ordered. The features are as follows (where D = 234 residues or 67 nm): (1) D-staggered collagen molecules 4.5 D long in the helical microfibril have a left-handed supercoil with a pitch of 400–700 residues, but microfibrils need not have helical symmetry. (2) Straight-tilted 0.5-D overlap regions on a near-hexagonal lattice contribute the discrete x-ray diffraction reflections arising from lateral order, while the gap regions remain disordered. (3) The overlap regions are equivalent, but are crystallographically distinguished by systematic displacements from the near-hexagonal lattice. (4) The unit cell is the same as in a recently proposed three-dimensional crystal model, and calculated intensities in the equatorial region of the x-ray diffraction pattern agree with observed values.

Heat Treatment Strengthens Human Dentin

2008 ◽  
Vol 87 (8) ◽  
pp. 762-766 ◽  
Author(s):  
M. Hayashi ◽  
E.V. Koychev ◽  
K. Okamura ◽  
A. Sugeta ◽  
C. Hongo ◽  
...  
Keyword(s):  
Heat Treatment ◽  
Stress Intensity ◽  
Type I Collagen ◽  
Type I ◽  
Third Molars ◽  
X Ray Diffraction ◽  
Intensity Factors ◽  
X Ray ◽  
Human Dentin ◽  
Triple Helices

The flexural strength of Type I collagen, the major organic component of human dentin, increases with heat. We hypothesized that human dentin can be strengthened by heating, which may help prevent fracture of non-vital teeth after restoration. Beam-shaped dentin specimens were obtained from the crowns of human third molars. The dentinal tubular orientations were arranged to run parallel or perpendicular to loading surfaces. The flexural and microtensile strengths of dentin in the parallel specimens were 2- to 2.4-fold greater after being heated between 110°C and 140°C for 1 hr. The stress intensity factors at fracture also increased after specimens were heated. The x-ray diffraction analyses suggested that shrinking of the lateral packing of the collagen triple-helices from 14 Å to 11 Å was the probable cause of the strengthening of heated dentin. We conclude that heat treatment strengthens human dentin.

Incommensurately modulated ordering of tetrahedral chains in Ca2Fe2O5 at elevated temperatures

2005 ◽  
Vol 61 (6) ◽  
pp. 656-662 ◽  
Author(s):  
Hannes Krüger ◽  
Volker Kahlenberg
Keyword(s):  
High Temperature ◽  
Single Crystal ◽  
Elevated Temperatures ◽  
Three Dimensional ◽  
Ambient Conditions ◽  
X Ray Diffraction ◽  
Modulated Structure ◽  
X Ray ◽  
Left Handed ◽  
Lattice Periodicity

The basic building units of brownmillerite-type A 2 B 2O5 structures are perovskite-like layers of corner-sharing BO6 octahedra and zweier single chains of BO4 tetrahedra. A three-dimensional framework is formed by alternate stacking of octahedral layers and sheets of tetrahedral chains. The compound Ca2Fe2O5 is known to have Pnma symmetry at ambient conditions. The space group Imma was reported to be evident above 963 K. New high-temperature single-crystal X-ray diffraction experiments at 1100 K revealed that Ca2Fe2O5 forms an incommensurately modulated structure adopting the superspace group Imma(00γ)s00, with γ = 0.588 (2). The modulation affects the sequence of the enantiomorphic (right- and left-handed) oriented tetrahedral chains within the layer, breaking the lattice periodicity along c. This ordering can be modelled with crenel occupation modulation functions for the tetrahedrally coordinated Fe, as well as for the O atom interconnecting the tetrahedra.

The crystal structure of schairerite and its relationship to sulphohalite

1975 ◽  
Vol 40 (310) ◽  
pp. 131-139 ◽  
Author(s):  
L. Fanfani ◽  
A. Nunzi ◽  
P. F. Zanazzi ◽  
A. R. Zanzari ◽  
C. Sabelli
Keyword(s):  
Crystal Structure ◽  
Diffraction Data ◽  
Hexagonal Lattice ◽  
Three Dimensional ◽  
Chemical Formula ◽  
X Ray Diffraction ◽  
Cell Content ◽  
X Ray ◽  
Structural Framework ◽  
Unequal Number

SummaryThe crystal structure of schairerite from Searles Lake, California, has been determined employing X-ray diffraction data collected on a single-crystal diffractometer. The crystal structure was refined by least-squares methods employing isotropic thermal parameters to a final R index of 0·07 for 2536 independent observed reflections. The cell content is 3[Na21(SO4)7F6Cl]. The space group is P31m with a 12·197 A and c 19·259 Å. Schairerite exhibits a marked sub-cell (a 7·042 Å, the same c axis and P3m1 symmetry), which may be related to the unit cell of sulphohalite when described in a hexagonal lattice.The crystal structure of schairerite may be considered as consisting of seven sheets of Na+ ions perpendicular to the c axis. These sheets are connected to each other .building up a three-dimensional framework. The Na+ ions in these sheets are arranged in an array built up of hexagons and triangles. Sulphur atoms lie in the sheets at the centres of each hexagon, the halogen atoms lying between the sheets midway between the centres of two triangles. A comparison with sulphohalite shows that the close lattice analogies may be related to a similar atomic arrangement. Apart from the differences in chemical formula (F:C1 ratio 1:1 in sulphohalite), the main difference in the structural framework consists of the unequal number of Na+ sheets (six in sulphohalite) and in the SO42− tetrahedra orientation.

scholarly journals X-ray diffraction studies of enkephalins. Crystal structure of [(4′-bromo) Phe4,Leu5]enkephalin

1984 ◽  
Vol 218 (3) ◽  
pp. 677-689 ◽  
Author(s):  
T Ishida ◽  
M Kenmotsu ◽  
Y Mino ◽  
M Inoue ◽  
T Fujiwara ◽  
...  
Keyword(s):  
Crystal Structure ◽  
Least Squares Method ◽  
Heavy Atom ◽  
Three Dimensional ◽  
Diffraction Method ◽  
Biologically Active ◽  
Type I ◽  
X Ray Diffraction ◽  
X Ray ◽  
Relationship Of

In order to investigate the structure-activity relationship of [Leu5]- and [Met5]enkephalins, [(4′-bromo)Phe4, Leu5]-, [(4′-bromo)Phe4, Met5]- and [Met5] enkephalins were synthesized and crystallized. The crystal structure of [(4′-bromo) Phe4, Leu5]- enkephalin was determined by X-ray diffraction method using the heavy atom method and refined to R = 0.092 by the least-squares method. The molecule in this crystal took essentially the same type I' beta-turn conformation found in [Leu5]enkephalin [Smith & Griffin (1978) Science 199, 1214-1216). On the other hand, the preliminary three-dimensional Patterson analyses showed that the most probable conformations of [(4′-bromo)Phe4,Met5]- and [Met5]enkephalins are both the dimeric extended forms. Based on these insights, the biologically active conformation of enkephalin was discussed in relation to the mu- and delta-receptors.

The Effects of Different Hydroxyapatite/TiO2 Composite Coatings on Protein Expression of Osteoblast

2009 ◽  
Vol 610-613 ◽  
pp. 1104-1108 ◽  
Author(s):  
Jian Ye Han ◽  
Zhen Tao Yu ◽  
Lian Zhou
Keyword(s):  
Protein Expression ◽  
Type I Collagen ◽  
Composite Coatings ◽  
Type I ◽  
X Ray Diffraction ◽  
Rt Pcr ◽  
Chain Reaction ◽  
Compound Formation ◽  
X Ray ◽  
Polymerase Chain

Hydroxyapatite/TiO2 composite material was coated onto Ti25Nb3Mo2Sn3Zr (TLM) alloy substrate. To study the effects of hydroxyapatite/TiO2 composite coatings on bone-related protein expression, the osteoblast were cultured with composite coatings for different times. The phase transformation and compound formation of the HA/TiO2 coatings were investigated using XRD (X-ray diffraction). The mRNA expression of Type I collagen, alkaline phosphatase (ALP) and osteocalcin were studied by RT-PCR (reverse transcriptional polymerase chain reaction). The titania delayed the crystallization of HA. The mRNA expressions of Type I collagen are decreased as the increasing of TiO2 percentage. The mRNA expressions of osteocalcin are approached. The ALP expression on H4 coating (HA/TiO2 mol ration is 5) after the osteoblast cultured with composite coating for 6 days is the highest. The increasing of TiO2 amount decreases the bioactivity of the composite coatings.

Isolation, ultrastructure, and partial characterization of collagen from the perineurium of the Florida lobster, Panulirus argus

1991 ◽  
Vol 69 (8) ◽  
pp. 531-536
Author(s):  
Roy J. Baerwald ◽  
Lura C. Williamson ◽  
E. Stevens ◽  
C. Rike ◽  
S. Trabanino ◽  
...  
Keyword(s):  
Amino Acid ◽  
Protein Content ◽  
Type I Collagen ◽  
Carbohydrate Content ◽  
Panulirus Argus ◽  
Computer Assisted ◽  
Type I ◽  
X Ray Diffraction ◽  
X Ray ◽  
Fibril Diameter

Highly concentrated extracellular filaments in the perineurium of the Florida spiny lobster, Panulirus argus, were isolated using ultracentrifugation and linear sucrose gradients. The pellet obtained was highly enriched for the filaments as observed by transmission electron microscopy. Fibril diameter and axial periodicity measurements were obtained from filaments positively and negatively stained with uranyl acetate. A period between 14.0 and 25.0 nm and an average fibril diameter of 15.0 nm were observed. The filaments proved resistant to solubilization by most conventional agents and by several collagenases. NaOH (0.1 M at 100 °C) safely dissolved the filaments for measurements of protein content by the Lowry method and carbohydrate content with anthrone reagent. These tests revealed a protein content of ≈ 84% and a high carbohydrate content of ≈ 15%. Polyacrylamide electrophoresis of an acid-pepsin filament extract revealed a highly concentrated band (approximately 100 000) corresponding to the α-1 and α-2 bands of vertebrate type I collagen. Wide angle X-ray diffraction yielded meridional reflections that confirmed the filaments as collagen when compared with mammalian collagen X-ray diffraction. The amino acid composition was determined with a computer-assisted Beckman amino acid analyzer, which showed a glycine content of 279 residues/1000. Hydroxylysine and hydroxyproline were present in lower concentrations than expected.Key words: perineurium, lobster, collagen, extracellular matrix.

HAp Protein Composites Formed by Hydrolysis of α-TCP

2005 ◽  
Vol 284-286 ◽  
pp. 39-42 ◽  
Author(s):  
Ahmed H. Touny ◽  
Paul W. Brown
Keyword(s):  
Type I Collagen ◽  
Isothermal Calorimetry ◽  
Protein Structures ◽  
Structural Proteins ◽  
Surrounding Tissue ◽  
Type I ◽  
X Ray Diffraction ◽  
X Ray ◽  
Hydrolysis Of ◽  
Aggressive Effect

Composite material composed of hydroxyapatite (HAp) and structural proteins, such as type I collagen or cross-linked gelatins, were synthesized at 37.4°C by hydrolysis of alpha tricalcium phosphate (α-TCP) in the presence of these protein structures. X-ray diffraction (XRD)and isothermal calorimetry were used as tools to evaluate the rate of HAp formation. Rates of HAp formation depend on protein structure. Gelatin enhances HAp formation while collagen delays it. Changes in pH during the hydrolysis α-TCP are unlikely to have an aggressive effect on the surrounding tissue. The presence of the protein improves the ductility of the HAp/protein composite but it decreases the tensile strength.

Solid State Ordering of Wholly Aromatic Copolyesters of Random Monomer Sequence

1993 ◽  
Vol 321 ◽  
Author(s):  
J. Blackwell ◽  
A.-I. Schneider ◽  
C. M. McCullagh
Keyword(s):  
Random Sequence ◽  
Hexagonal Lattice ◽  
Three Dimensional ◽  
X Ray Diffraction ◽  
Molecular Mechanics Calculations ◽  
Polymer Systems ◽  
X Ray ◽  
Monomer Sequence ◽  
Naphthoic Acid ◽  
Diffraction Patterns

ABSTRACTX-ray diffraction and computer molecular modeling Methods are being used to investigate the ordering of random sequence copolyesters when cooled for the nematic Melt. Data will be presented for the copolymers prepared from p-hydroxybenzoic acid (HBA) and 6-hydroxy-2-naphthoic acid. The non-periodic diffraction patterns arising from the random monomer sequences are also indicative of the presence of limited three dimensional order. For both polymer systems, we can generate the qualitative feature of the x-ray data using models in which short non-identical segments of 10–12 Monomers on adjacent chains are approximately in register at their center. Molecular Mechanics calculations show that mese non-identical sequences can be packed on the observed hexagonal lattice with only small energy differences when compared to analogous homopolymer structures. Data will also be presented showing how x-ray diffraction can be used to follow transesterification of copoly (HBA/HNA) in the nematic MelL

Ribosome Structural Organization

1974 ◽  
Vol 32 ◽  
pp. 332-333
Author(s):  
James A. Lake
Keyword(s):  
Ribosomal Proteins ◽  
Structural Organization ◽  
Three Dimensional ◽  
Small Subunit ◽  
Structural Studies ◽  
X Ray Diffraction ◽  
Specific Antibodies ◽  
X Ray ◽  
E Coli ◽  
Complete Sequences

The understanding of ribosome structure has advanced considerably in the last several years. Biochemists have characterized the constituent proteins and rRNA's of ribosomes. Complete sequences have been determined for some ribosomal proteins and specific antibodies have been prepared against all E. coli small subunit proteins. In addition, a number of naturally occuring systems of three dimensional ribosome crystals which are suitable for structural studies have been observed in eukaryotes. Although the crystals are, in general, too small for X-ray diffraction, their size is ideal for electron microscopy.

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